Monday, November 20, 2017


Digital Hotspots

Two hotspots are in use in the EI5DD QTH. The Shark RF Openspot and the DVMega bluestack. They are both excellent Hotspots and result in an excellent signal through the Netork to which they are connected. Other Hotspots include MMDVM and the DV4Mini.

A Digital Hotspot is a standalone digital radio IP gateway connected either directly to the Internet router via WiFi, Bluetooth or direct connection. Effectively, it is a small transceiver which transmits auudio derived from the internet connected to an appropriate Network such as Brandmeister, YSF or FCS.

The DVMega comes in two forms, either UHF only or dual band UHF and VHF.

The DVMega comes with a USB programming lead allowing the Firmware to be updated as required and the lead will double as a direct connection to a computer, Raspberry pi or windows,  or Android phone/tablet or is used to power the device. 

The initial set up of the device on a  windows system is simple by filling in the appropriate boxes with the reuired information and ensuring the correct frequency

A similar, but simple, screen is available on the Andriod tablet or Phone.

Monday, September 11, 2017

DMR Code Plug Programming

DMR Code Plug Programming for the Tytera MD-380

Ask anyone if they are going to get into Digital radio and the immediate reply is NO it is too complicated. Why? The stock answer is that it cannot be taken out of the box and placed on air without having to program it up first. Take one look at the Programming Software and it is not hard to understand. The Software allows the programming of a "Code Plug", which is essentially the "personality" of the radio. The radio can only transmit and receive on the channels programmed into the code plug. An RTFM problem before one starts!

If you have not acquired a DMR ID then go to this location:  Follow the instructions and have a PDF copy of the front page of the licence to upload completing the registration process. The ID is issued within a day or two. Follow the steps below and programming will become second nature. Rome wasn't built in a day, and neither will your code plug!

The order in which the programming is done is as follows:

1) Contacts
2) Channels
3) Zones
4) Placement of channels into Zones.

The program for the individual radio is either down-loadable from the manufacturer's website, or on the disc supplied with the rig. In this write up, it is the Tytera MD-380 or clones such as the Retevis or Zastone handhelds that will be described. 

On running up the program this is the first screen that will show on the screen

If the set is a UHF handheld, then this is the basic information seen. Attach the programming lead supplied with the radio and then switch the radio on. Look along the toolbar of the program as seen above and to the right of the disc symbol there is a picture of a handheld radio with a white arrow pointing to the left. Click on this and anything programmed into the radio will be downloaded to the program on screen. Normally, there is one channel as an example. The view shown is the Basic Information which is the first item in the menu.

General Settings

Click on the general settings and the screen below will pop up.

Look at the positions highlighted by red arrows. The Radio Name is your callsign and this is typed in Capital Letters. the Radio ID is the DMR registration number assigned to your callsign. The two boxes shown on the bottom right of the screen can contain in Line 1 - your Name and Line 2 - your Callsign. These may be left blank and will not affect the operation of the radio. Best to leave any other settings alone until you have a greater understanding of their consequences!


On the menu, click on Digital Contacts and this screen will pop up

Click "Add" at the bottom of the screen. Enter the name of the contact in the "Contact Name" box - it is possible to replace the words Contact 1 with the name required. Click on "Call Type" and three options will be available on the drop down menu. Most calls will either be "Private" or "Group". Enter a contact here which may be an Individual, a Reflector, or Talk Group.  

Any number of channels can be added to this box for future use.

To program a channel such as the Ireland Calling Channel the layout would be as follows:

No    Contact Name                   Call Type             Call ID

 1     Ireland Calling                    Group                  2722

 2         EI4ALE                          Private               2720045

Ireland Call is the Irish Calling Channel it is a Talk Group and will be a group call so all can hear that call when it is made. 2722 is the DMR ID for that talk Group.  EI4ALE is a Private Call so when the call is made it will only be directed to that individual in this case the DMR ID is 2720045. On completion of the contacts screen, the next task is to assign channels.


On the menu in the left hand column, Click on  "Channels Information" and the following screen will appear

All of the positions with red arrows need to be filled in the following order

Channel Name -   From our Example above this one can be named Ireland Calling Channel 
Channel Mode -   Generally defaults to Digital but, if not, the drop down menu will allow selection
Frequency -         Your choice of Frequency for the RX and TX frequencies
Contact Name -   Click on the down arrow and all of the contacts will display - choose the Ireland
                          Calling Channel
Colour Code -      This is can be any number 1 - 15 but generally set to 1 unless otherwise required
Repeater Slot -    Can only be set to 1 or 2 - in our case we set this to 2
TOT (s) -             Set to 180s for network operation. Most Network items time out after 3 mins
Power -               Set to Low power if using a Hotspot but, set to High power if going through a

Best not to alter any of the other settings unless you have read more about them.

It is possible to program in Analogue channels by selecting Analog in the Channel mode. The method is the same as for Digital Channels. CTCSS can tones can be added if the Analog mode is selected.

Use with a Hotspot e.g. DVMega or Shark Openspot

If it is planned to use the Hand Held Radio with a hotspot or Local Repeater it is essential to program the TX and RX frequency to suit that of the device in question.


There are a maximum of 16 Zones selectable on the average Hand Held Radio. These can hold up to 16 channels.  This equates to a total of 256 channels. This allows one to sort their channels into specific Groups held in each Zone.  

By "right clicking" the mouse on the Zone information, a small tab with "Add" will appear click on that and this will add a Zone into the list. Do it several times and there will be a few more Zones added. 

Click on Zone 1 in the menu and the screen shown will appear. This Zone can be renamed by back spacing over the Zone 1 name and giving a relevant name for the channels contained therein. 

To add Channels to the Zone, available channels will be listed in the left hand column. Click on a channel in the list as in the case of channel 2 which will become highlighted. 

Click the add button in the centre of the box and the channel will be added to the zone as in the case of Channel1 already in the channel member box.

16 zones may be programmed with channel members. 

That completes the basic programming. Anything that was not highlighted with a red arrow is best left alone!

Setting up a scan list

The scan list may be set up by clicking on "Scan List in the side menu. To add more than the one Scan list, "right click" the mouse whilst pointing at Scan List and an "Add" tab will appear so click on that also. Selecting a scan list after clicking "Scan list" on the menu will result in the following screen 

To add channels to the scan list, click on the desired channel in the left hand column and then click "Add" in the centre of the box and the channel will move across. Only 16 channels may be selected for each list.

Once programmed into the Radio, the scan list can be selected from the keyboard. The rig may be set to scan by programming one of the buttons on the side of the radio. Go to the side menu and select "Buttons Definitions" and the following screen will appear

Go to the "Radio Buttons" box and click on the pull down menu for "Side Button 1". Click on Scan On/Off. After this, select the pull down menu on "Side Button 2" and change this to "High/Low Power" which may be selected from the contents of the pull down menu.


Give the program a suitable name like your callsign followed by code plug. Save this, and if you wish to change anything always save the changed file with a new name. Code plugs take time to build and it would be a shame to overwrite work already done. ALWAYS keep the original copy so you can have a reference point from which to start.

It may seem laborious at the start, but after a few times it will become logical and second nature. If you have mastered the steps demonstrated, you will be able to program most other transceivers with little difficulty. It will be found that other more complex rigs, like the Motorola, follow a similar pattern.

USERS OF THE Radiodity GD - 77  - Use the Radioddity CPS Program for the GD-77

Using the Radioddity CPS Software is similar to setting the Tyera MD-380. Follow the sequence above to set up the Contacts, Channels, Zones, and placement of Channels in the Zones. However, there are a couple of extra steps required to get the radio to receive the channels on which it transmits.

Rx Group List - if this part is not completed it will not receive anything

It is necessary to set up a Receive Group List for each batch of channels. Right click on the "RX Group List to add a new list and give it a name. Highlight the channel to add and then hit the"Add" button in the centre. In the example shown, the IRL SERVER is the name of the RX Group List and the Three channels have been added

The Channel List

Go to the Channels list and double click on the desired channel which willresult in the screen shown below:

On the right hand side, click on the RX Group list pull down box and, in this case select the Ireland Server. If you haven't already named the contact, click on the pull down menu next to contact name and select the relevant name for it from the list. Generally all contacts here would be Color Code 1 and Time Slot 2. unless otherwise required.

Make sure The Callsign and name are added into the Boot Item. Add the Callsign and Radio ID (DMR Registration) into the General Settings. That completes the Code plug. Save a working copy and save a User Copy under your own callsign.

If it is not possible to change the information in the Boot Item list perform the following task:

With the Program Software up and running on your computer, press and hold CRTL, ALT, SHIFT, and press F11 at the same time. A pop up window will appear. Type  DMR961510 into the box and this will give "expert facilities and open up a few other facilities not normally required for programming a routine CPS.

Best of Luck with your efforts  .......

Saturday, March 18, 2017

Experiments With Yaesu Fusion

We now have four stations in Galway operational on Yaesu Fusion. 3 have FTM400XDR transceivers and the other has a FTM100. Two in Mayo should be on shortly so the efforts have finally borne fruit. Possibly another FTM100 in Galway shortly. There is another operator who ownes a Yaesu FT991. Nine on the air in a short time is a great effort.

The Limerick area, due South of Galway,  have a Yaesu Fusion Repeater which provides a good signal throughout Galway and into Co. Mayo as far west as Westport. The current number of Fusion operators in the Limerick area would appear to be around ten or eleven.

Plans are to place a Wires-X gateway online by the end of April, which will serve Galway City and the surrounding area of 25 Km radius.

The first experiment was carried out between EI3FEB in Headford and myself in Galway City - a path of 23.5 Km but it had a few hills in between the two stations so was a poor path at the best of times. The path was chosen as this was probably the worst signal strength achievable.

Both rigs were set up to transmit 5 watts and the initial transmission was made on FM 

As can be seen on the display the signal strength did not even register and the FM signal had the usual hiss encountered with FM signals received on the fringe area. For an S0 signal it was not too band. The FTM 400 recorded the returned signal as S0.5 - S1. Readable with plenty of hiss. Note the FM displayed to the right of the frequency displayed indicating this was in the FM mode. The lower green light indicates FM reception.

The mode was changed to C4FM and the signal received was most impressive 

This signal was still received at a S0 level but his time in C4FM. The quality of audio was crystal clear with absolutely no background noise. Note the DN displayed to the right of the frequency displayed denoting in digital mode. The blue light denotes the reception of a digital signal. When the digital signal is received other information is embedded within it which includes the Callsign and also GPS coordinates. The distance as shown was derived from that information.

Check out the YouTube video
Quite impressive with  no R2D2 sounds from the received signal.

More to follow   ..........................

Saturday, February 4, 2017

Yaesu Fusion

Yaesu Fusion has been established in the West of Ireland by the Limerick Radio Club on both 2 metres and 70cms. The Limerick Repeater has been operational on System Fusion for over a year and more recently the 70cms Repeater has been installed. Wires-X is not connected so the Limerick Repeaters are specifically just acting as Repeaters and not able to connect to the rest of the world. Donegal also has a Fusion Repeater and this is connected to the Wires-X system. 

Yaesu Fusion radios are Dual Band and Dual Mode which makes them more versatile. As a result it is possible to experiment with direct point to point simplex communication. Regrettably not a lot of individuals have the equipment as yet and there are also rival modes like DMR and perhaps the older D-Star.

The DV4Mini set up for Yaesu Fusion

Using a DV Megga Bluestack or a DV4Mini, it is possible to connect into some of the many Yaesu Fusion Talkrooms. There a huge number and each area of the world has its own designated area or indeed some common or shared areas.

Of late there has been a number of talkrooms linked together in the UK resulting in a huge increase in activity in one particular area. It has even been possible to cross conect from DMR to Fusion a vice versa. Sometimes up to 80+ have linked ot this area.

A screen grab of a busy Yaesu Fusion Talk Room from the DV4Mini Control Panel

So far there have been no Fusion contacts on the Limerick Repeater despite a number of E-mails requesting a sked to try the system out. The transmissions do go through the Repeater without any problem but alas no replies.Undoubtedly this area will increase in activity as more become involved.

The initial feeling is that Yaesu Fusion does have better quality over the other modes. Most of the equipment is dual band so there is an opportunity to work through more repeaters and gateways. Fusion does lend itself to more point to point simplex communication on both 2 metres and 70cms. Repeater and gateway activity may also promote this mode.

The Disadvantage with Fusion is that it is a propriety mode and cannot be copied by any other company other than Yaesu. DMR may possibly become more popular with the number of cheaper Chinese tranceivers and handhelds. DMR is more of an open source mode and not confined to any one manufacturer making it more attractive. A bit like Betamax and VHS - which standard will ultimately win. It is possible that there are still other Digital systems that have not yet been released.

Friday, December 2, 2016

The Digital Bug Continues

Having gotten the bug for Digital Voice operation and the obvious way to go on VHF or UHF is via one of the many modes available of late. C4FM, D-Star, or DMR - Which one?


They all have their attributes but in order of complexity the C4FM seems to be the first choice and easy to set up. The mode is more modern has a lot going for it and any signals heard seem to be of great quality. There is a C4FM repeater in my locality, located in Limerick. There is nothing for other modes. A DV4Mini access point would be an ideal soulution to hooking into a network which will give me contacts. A bit like a complicated EchoLink all the same. I have my mind set on purchasing a FTM-400XDR which has all the facilities on it including APRS.

This rig is analogue and C4FM  and also has built in GPS for APRS operation. Strangely a handheld is quite expensive for this mode of operation so probably better to get the mobile rig and done with it. I was never a huge fan of Handheld operation.

Strangely one has to register for a DMR I/Dnumber so as to set up a Hotspot such as a DV4mini or DVMegga system. Not a complicated situation but it is necessary to scan in the front page of the licence as proof that it is you applying.


Slightly more complex to set up  and I/D number is required which obviously links to the Callsign. Code Plugs are required. Programming isn’t too complicated once you understand the concept of Slots, TalkGroups and Zones.  All of these parameters have to be programmed into the code plug. Perhaps it is best to join a local group in the area who will have a downloadable code plug which is far easier.

A code plug is simply a radio's configuration file. Using the Manufacturer's programming software, it is possible to configure the channels and operating parameters of the radio. This file is uploaded to the radio and should be saved on the computer as backup. Downloadable codeplugs from local user groups are probably the best way to go.

An excellent bargain was found on  The Zaston D900 handheld x 2. At the price shown they were perfect for experimentation and did not break the bank. A handheld, but it is an entry level into the area of DMR. The offer only lasted a couple of weeks and the batch was sold out and then reposted for a larger fee. He who hesitates is lost!

I was informed that these are a clone of the TYT MD-380 and with a Firmware Update and a local Code plug these will be more than enough to get started in to DMR. In the box, there are two handhelds, 2 chargers, a programming leads and an "Agent Smith" (Matrix) style microphone and earpiece. One does not have to use this arrangement.

Straight out of the box, it was possible to use the rig as the battery had a good charge. The Handhelds are of sturdy construction and the audio output is of excellent quality. A code plug with mainly Northern frequencies and Simplex channels was downloaded. After a bit of a struggle the rigs worked perfectly. The problem was a small error in the codeplug which was not compatible with my Hotspot. After some head scratching advice was sought and the problem rectified. Results were impressive.

Access Points

The DV4 mini is a small USB dongle working on 70 cms and provides a great starting point for Digital communications. The Raspberry Pi is linked via Wi Fi to the laptop where the control panel is displayed.

A DVMegga Bluestack dual band access point was subsequently puchased which is more versatile and stand alone. This has been in constant use with no problems encountered. This system is uses the Wi Fi from an Andriod tablet or mobile phone linked via bluetooth. The Android phone acts as the control panel although not physically connected. It is stable and the quality of signal is excellent.

The system works well with DMR and Fusion although D-Star has not been tested - there are limits! The new software is due out in 2017 and this will facilitate cross-mode connects e.g. DMR to Fusion etc.

Local Gateway/Access Point

I have recently procured the components for a triple mode gateway to allow access to D-Star, DMR and Yaesu Fusion. It will be made up from a Raspberry Pi, Arduino Due, an MMDVM board and a Mororola GM350 with minor modifications. Pictured below is the MMDVM seated on the Arduino Due which will connect to the Rasberry Pi.

The licence has been applied for at this stage so it is a matter of time before the go ahead is given. VHF was chosen as the range would be be better as opposed to VHF. We should be able to cover a 30 mile radius.

At least a start on the software has been made and construction which will get the system on air reasonably quickly. I think better to deal with project myself as the VHF Group Repeater is still waiting to be located on site after 3 years. Left to others, nothing gets done as there is not the same enthusiasm!

Friday, November 4, 2016

Adventures on Digital Voice Using the ARD9000MK2

An ARD 9000Mk2 was purchased some years ago at the same time as the Yaesu FTDX5000MP; a present to myself on retirement. Early experiments included recording the transmitted output onto a tape recorder and playing this back through the unit to hear the results. It worked fine. A second unit had been found at a rally and it was snapped up for a mere 20 Euro - a bargain. Until recently, nobody had ever been worked or heard on digital voice irrespective of the number of times the rig was left monitoring a supposed digital channel on any of the HF bands.

The ADR 9000MK2

The AOR Corporation were the first ham manufacturer to introduce a Digital voice "modem" in 2004. Their first unit was the ARD9800 which had the ability to transfer files. The ARD9000 was produced without the ability to transfer files and was a voice only unit and a little cheaper to purchase. The design of this unit was based on a VOCODER (voice encode and decode) protocol designed by Charles Brain G4GUO. His protocol involved the use of Advanced Mulit-Band Excitation (AMBE), a propriety speech coding standard developed by Digital Voice Systems.

The specifications of the ARD 9000Mk2  are as follows:

Modulation method:   
                                   Orthogonal Frequency Division Multiplexing (OFDM)
Bandwidth:                   300Hz - 2500Hz, 36 carriers
Symbol Rate:               20mS (50 baud)
Guard interval:              4mS
Tone Steps                   62.5Hz
Modulation method:
                                   36 carriers: DQPSK (3.6K)
AFSK                          +/- 125Hz
Error Correction:           Voice: Golay + Hamming
Hearder                       1 Sec. 3 Tones + BPSK training pattern for synchronisation
Digital Voice:                AMBE coder, decoder
Signal Detection:          Automatic Digital detect. Automatic switching
                                   between analogue and digital mode.

Description and Theory 

There are a few common elements to a digital voice system. The Modem converts a signal from the microphone, or another analogue source, to a digital bit stream. This is referred to as an A/D converter. This is driven by an algorithm referred to as a CODEC. The signal is then processed into a modulation waveform that can be applied to a radio transmitter. The received signal has to be converted to a digital stream e.g. demodulated. The digital bit stream is then demodulated to form an analogue waveform via a digital to analogue converter by a matching algorithm or CODEC to that applied to the transmitter. The resultant signal can then drive a speaker. This is the basic function of the ADR 9000MK2.  See diagram below:

 The basic blocks of a digital voice modem

OFDM is a form of multicarrier modulation. An OFDM signal consists of a number of closely spaced modulated carriers. When modulation of any form - voice data etc. is applied to the carrier, the sidebands spread out either side.

On analogue modes, it is necessary for a receiver to be able to receive the whole signal to successfully demodulate the data. When signals are transmitted close to one another, they must be spaced so that the receiver can separate them using a filter and there must be a guard band between them. 

This is not the case with OFDM. Although the sidebands from each carrier overlap, they can still be received without the interference that might be expected because they are orthogonal to each other. This is achieved having the carrier spacing to the reciprocal of the symbol period.

Traditional view of receiving signals carrying modulation

To see how OFDM works, it is necessary to look at the receiver. This acts as a bank of demodulators, translating each carrier down to DC. The resultant signal is integrated over the symbol period to regenerate the data from that carrier. The same demodulator also demodulates the other carriers. As the carrier spacing equal to the reciprocal of the symbol period means that they will have a whole number of cycles in the symbol period and their contribution will sum ot zero - in other words there is no interference contribution.

One requirement of OFDM transmitting sytems is that they must be linear. Any non-linearity will cause distortion amongst carriers as a result of inter-modulation distortion.  This will introduce unwanted signals that would cause interference and impair the othogonality of the system.


Immunity to Selective Fading: One of the main advantages of OFDM is that it is more resistant to selective fading than single carrier systems as it divides the overall channel into multiple signals affected individually as flat fading channels 

Resilience to Interference: Interference appearing on channel may be bandwidth limited and will not affect the sub-channels. This means data will not be lost.

Spectrum Efficiency: using close spaced overlapping sub-carriers, a significant OFDM advantage is that makes efficient use of available spectrum.


Hight peak to average power ratio: An OFDM signal has a noise figure like amplitude variation, and has a relatively large dynamic range, or peak to average power ratio. This impacts the RF amplifier efficiency as the amplifiers need to be linear and accommodate the large amplitude variations and these factors mean that the amplifier cannot operate with a high efficiency level.

Sensitive to  carrier offset and drift:  Another disadvantage of OFDM is that is sensitive to carrier frequency offset and drift. Single carrier systems are less sensitive.

In practice

A number of settings need to be performed before actually transmitting on air.

Ensure that the receiver is actually 100% on the same frequency as the other user. IF necessary, once the QSO is established, use the RIT.

The I.F. filters on the transceiver need to be set to 3KHz

Ensure that Speech compression and equalisation is switched off

Bear in mind that the duty cycle of the transmitted signal is around 100% so set the carrier level to a suitable power output in accordance with the radio specifications. 

Establish the initial contact on SSB and ensure that the resolution of the voice is perfect and the TX and RX are on the same frequency. This is essential. 

Ensure that the ALC meter shows no movement. If there is movement, back off the input from the modem using the mic gain from the transceiver. If the modem is a bit "lively" reduce the pre-set mic input on the mic pot on the underside of the modem. 

When transmitting pay attention to the overdrive light on the modem. Back away from the microphone or reduce the input to the modem.The overload light should seldom flash and occasional flash will not cause a problem.

It is a good idea to run the ARD9000 off a different supply to that of the rig. A small Gel Battery was employed to be on the safe side. This eliminates the possibility of a hum loop. Ferrite beads in the power line and on the mic lead will prevent any RF getting into the box. Again all precautionary. This will ensure that any poor decode is only down to mic gain on TX or input levels at the RX end.

The Receive settings:

Ensure that the modem is not overloaded watch the Overload light on the Modem. If it is flashing, the input to the modem is too low. If it remains off the input is optimal. If it remains on the AF input level is too high. These levels are dependant on the AF gain from the transceiver. The unit has its AF gain control for personal preference either through the speaker mic or via a lousdpeaker.

Results to Date

Initial work was carried out on 2 metres FM. Both myself and EI7GMB had never used the units before so this was a steep learning curve. Following successful results on 2 metres FM, SSB was tried with surprisingting results.

Using the Kenwood TM-D710, the following settings were applied. 

FM modulation:    Wide
Mic Sensitivity:     Low
AF gain:              Set as required
The mic output pre-set found underneath the unit was reduced in gain slightly. 

Operation on FM

Surprisingly, this process was not painful. In the initial stages, everything broke up and the decode was erratic until levels were correctly set at each end. Everything came together quickly and 2 way communication was possible with comfortable decode. The reproduction of the voice was excellent and both sides achieved good results. A reduction of power between the stations was disappointing. When the carrier was not fully quieting, the noise was too great for the unit to overcome. This resulted in almost incoherent signals. Back up to a fully quieting FM carrier gave good results once again. 

A trip onto the Limerick voice repeater was made. The signal of the repeater was good on both sides of the transmission. The results were excellent from the digital signal transmitted through the Limerick repeater. The received signal was flawless. 

It was concluded that Digital Voice would be excellent over a good path on FM but not at fringe levels where the carrier is noisy. Mobile operation has not yet been tried but will be the next test on the agenda.

The problem with the FM is that the digital carriers are superimposed on the one FM carrier. If the carrier received over a distance is noisy then the whole signal breaks up. Conclusion that digital voice needs a quiet carrier to be received well. Digital is either there or not there. How does D-Star cope or any of the other digital modes? This would be interesting to observe the difference.

Operation on SSB

Connection to the Icom 756 tranceiver was simple and the operation required a few pre-sets to be made, for example, the microphone gain, the power level and above all observation of the ALC meter.

It was necessary to initiate the QSO on SSB and ensure that both tranceivers were on the exact same frequency.  If adjustment has to be made, once in the QSO,  use the RIT. This having been done the mic gain was increased to give about 30% power output and with care to observe the ALC meter. Whilst transmitting the overload LED was observed, ensuring that the signal did not overload the modem. 

The results were impressive and feedback via 2 metres proved that the signals were being decoded properly at each end. Reduction of power levels made no difference with a 5 watt level emanating from my own radio. The path was not too distant so this probably would have made no difference. This may be reduced further to see how the decode occurs with a weaker signal.

The results overall were excellent and the mode did everything it was supposed to do. Voice reproduction was similar in quality to FM and overall via SSB, the quality as good. 

SSB obviously allows this mode to come into its own. The 32 carriers were independent of a carrier as used in the FM mode. The modem captured the signal so much better and indeed as it was designed to do. 

There is no doubt that with care and attention, this mode is far better suited to SSB than for use on FM. 

The AMBE codec is the same as that used in D-Star, C4FM, and the commercial DMR. The unfortunate side, is that each mode employs a different protocol and none are compatible with each other. This results in a divided community. All the modes work perfectly within their own community. 

The fact that there are so many different digital modes will never allow one to take off in any great numbers. In Ireland, the ham community is small and there would have to be some standard to suit all. Would it be D-Star, C4FM or DMR at the end of the day. It is not going to be viable to buy one of each! With the AOR system, it can be interfaced to any radio whether on HF or VHF as it is literally plug and play. The Chinese manufacturers are beginning to take an interest in the digital market and will no doubt gravitate toward the DMR commercial standard as this would appear to be a more viable market with cheaper equipment. Hopefully they will not introduce yet another protocol.

This summarises the work to date, but if there are any other major developments, they will be added to this text.

Further information: It is wise to ensure that RF does not get into the set up. Ferrite beads of clip-ons around the mic lead and also the power lead may help. Experiments performed to date have used an alternative power supply to that used by the transceiver. This could be a small gel cell or a bank of NiMH batteries. The literature suggests that this is a good idea to prevent loops and any distortion being added to the signal.

Power levels: These have been reduced to 0.5W with no problem. Signals decoded well and the comparison to analogue was way different. The Digital still came out with 100% clarity and no background noise compared with the analogue signal  which was noisy.

YouTube link to results of a brief test    Click Here

Tests currently take place on 28.330MHz or 144.600MHz


If there are any EI or UK stations using the AOR fast modem please drop me an E-mail as I would like to try a few contacts outside of Galway City.

Saturday, April 2, 2016

Kenwood VC-H1 Visual Communicator

Having got involved with the transmission of DATA over the airwaves, SSTV was bound to feature at some stage of the proceedings. After great success using MMSSTV and DM780's SSTV software on HF, it was apparent that this would be an interesting mode to use on VHF/UHF. It would certainly be more conducive with interference free pictures if used via the FM mode and better again it would be possible to send these via a Repeater if one really wanted to go from point to point. 

This does smack of Toys for Boys a bit, but in fairness, I could see the possibilities with our Emergency Communications Network and who knows where they may fit in. One very interesting application would be during the Galway Regatta where live feedback from the finish line would be a superb addition to the operation.  "A picture paints a thousand words".

My set up in the shack is very much tied to a desk top computer and obviously not geared for portable operation. Lap tops are a dead loss as they tend to be slow and very clunky and generally die at the most inopportune moments.

Enter the VC-H1 visual communicator manufactured by Kenwood some time ago during the 1990's. There are still a surprising number of these items out there either second hand and barely used or even still brand new and never sold.

The Kenwood VC-H1 Communicator 

Essentially the VC-H1 acts as a rather cumbersome Speaker Microphone when attached to a compatible handheld or the Kenwood TM-D700. To the left of its screen, the PTT and picture capture buttons are located.  The camera is located on the top of the unit and this can be swiveled for selfies, if absolutely necessary, or pointed in the direction of the subject. The 1.8 inch monitor screen is a little on the small side but is adequate for the majority of my needs. Received pictures can be stored in memory and can be re-sent to their originator. The pictures may be downloaded onto a PC if required. 

The transmitted and received pictures are sharp and clear and not too bad considering that they are received on such a small monitor. Images are transmitted from a  1/4-inch, 270,000-pixel CCD camera and seem to be good in most lighting conditions. The quality being about as good as a standard Web Cam.

The unit comes with a standard lead for connection into a Kenwood Handheld and this is also compatible with the Wouxun and Baofeng Handhelds. If used with these handhelds two modes are available in the form of Robot 36 colour, and Fast FM. If used with a Kenwood compatible handheld or the TM-D700 the unit is capable of operating the following modes in addition: Robot colour 72 , Scottie S1, Scottie S2, Martin M1, Martin M2, and AVT90.

Leads for this unit are expensive and very hard to come by especially the lead that connects into a PC and to the TM-D700. Of course if this lead is used the unit is extremely versatile as images may be uploaded and downloaded and the unit can be interfaced to a much more powerful tranceiver. 

Currently, the VC-H1 is being used to transmit pictures from the International Space station. Considering the distance travelled, the images are very good.

 Pictures Transmitted From the International Space Station

It is planned to hook this unit to the HF equipment although sending Selfies from the shack is really under utilising this type of equipment and I am not that vane! I would suspect that applications such as hill-walking and some of our outdoor activities may be enhanced with the use of this equipment.

Selling points

In addition to the detachable 1/4-inch CCD camera, the VC-H1 features a 1.8-inch color TFT (thin film transistor) type display. As well as viewing incoming pictures, you can review your own prior to transmission. The built-in microphone & speaker can be used in place of a separate speaker-microphone for your transceiver.

Up to 10 pictures can be stored in memory. This allows you to compare and pick the best shot to send. You can also store incoming pictures and protect them from unintentional deletion.

One of the great features of the VC-H1 is its ability to work with a personal computer. Hook it up to the RS-232C port on your laptop using the optional connection kit Microsoft Windows and you can save pictures (in JPEG format) that you send and receive. You can then cut and paste using standard graphics software, or even superimpose your own text. What's more, you can actually control the VC-H1 from your computer.

The Not so Good Points:

The unit requires 6 volts to operate and so is not great for mobile operation. It uses 4 AA batteries and these do not last too long with constant use. It does, however, work on 4 rechargeable AA batteries which is some consolation.

When you have bought one of these units it does become apparent that you need a second one if you want to get any fun out of it. It is no good relying on a friend to buy one or even hope that they will be on air if they do have one.

Interconnecting leads are expensive and as rare as hobby horse's droppings. The small connector into the unit costs more than 20 Euro. Any external leads have to be home-brewed apart from the lead connecting to the Handheld which they did include in the box. 

Lead wiring for TM-D700 and also for the PC