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?

C4FM

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.

DMR

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 Amazon.com  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!