Friday
Jul052013

G4KLX software running on an Odroid-X board

I've finally had some success with getting the G4KLX ircDDB Gateway and Repeater software running on my Odroid-X board.

 

The Odroid-X is a ARM based development platform from Hardkernel in South Korea.  The Odroid-X has been replaced with the Odroid-X2, but it's basically the same board with a faster processor and more memory.

I'm using the Linaro Linux distribution on the Odroid-X and I ended up being quite ruthless with stopping unnecessary services that weren't required for the G4KLX software to operate.

Some services that are no longer running include Bluetooth, Modem Manager and the GUI/HDMI system. I have to be careful that I don't kill the network, this is the only way I can communication with the board. There is a debug port that allows serial terminal access, but I don't have the level converting interface board at the moment.

In the YouTube video I mention that the Repeater software needs some "encouragement" to start up. I think the Modem Manager was the main culprit that stopped the Repeater/dvapnoded software from starting.  I noticed the blue LED in the DVAP Dongle blinking several times during boot, something was trying to "talk" to the DVAP Dongle on TTY0.  Disabling Modem Manager seemed to fix this.

I've now set up the Odroid-X to use a MoenComm GMSK modem & Motorola MCS2000 UHF radio and it seems to be working very well!

P.S.  I now see on the Hardkernel forums that an Odroid-X user has compiled a cut down "server" version of the Linaro distro.  I've download the image file and might try it out and see how it performs "out of the box" with the G4KLX software.

 73

Monday
Jun172013

Another transportable D-Star HotSpot project!

I recently received an email from Devon VE5DWR in Saskatoon, Canada. He updated me on his portable D-Star HotSpot project.

http://24.72.16.22/saskatoon-dstar/portablegateway.html

Devon used a Pelican 1300 case (larger than the one I used) and has used the extra space to include an LCD screen in the lid, wireless keyboard & industrial strength powered USB hub.  The antennas for the 70cm and 2m DVAP Dongles mount on the lid of the case. Fan cooling ensure the equipment inside the case remains cool with the lid closed.  The TP Link router is mounted under the DVAP Dongles.

Devon uses the FreeStar* software from Ramesh VA3UV running on a Raspberry Pi computer. 

You can see some more photos in this gallery.

Thanks Devon for allowing me to use your photos in this blog entry!

73

 

Friday
May242013

DV-RPTR V3.0 looks very nice!

It seems like only yesterday I blogged about the DV-RPTR V2 board with it's striking white solder mask and attractive yet functional enclosure.  

http://vk5rex.squarespace.com/blog/2012/10/18/dv-rptr-board-version-2.html

This week I'm reading about DV-RPTR V3.0, the latest creation from the DV-RPTR team in Germany. The user manual has been released and kindly translated into English by N1DL!

The larger colour LCD screen is the first thing you notice. Although the V2 monochrome OLED screen had a reasonable resolution, it was small.  The new screen is a welcome addition and colour is sure to enhance functionality.

The AMBE board, Ethernet board and (when it is released) iTRX board are all modular and plug into the main V3 board.  I'm not sure if you can purchase add-on boards at a later time, but knowing how fast the DV-RPTR project has evolved over the last few years you should probably get any add-ons you could possibly want sooner rather than later!

The rotary control is backlit and the illumination changes depending on the operational mode providing the user additional feedback. 

When (hopefully not if) the iTRX board makes an appearance... the DV-RPTR V3.0 (and AMBE board) will essentially be the first non-Icom D-Star compatible radio, a device that can be used standalone without the need for an attached computer or external radio!  You can use the DV-RPTR V1 and V2 without a computer, but you do need to plug them into a radio.  I've not seen specifications on the iTRX board, it certainly won't be a 50 Watt radio, but even 1 Watt would be quite useable... 5 Watts would be better. I presume all the familar DV-RPTR operational modes will be available including HotSpot.

The DV-RPTR V3.0 looks very very nice... can't wait to see it in operation!

73

Thursday
May022013

The mysterious Icom ID-RP2C analog/digital switch

When I received my D-Star repeater equipment from Icom Australia in 2008, the first thing on my to-do list was to pop off the covers and take a look inside!

Inside the Icom ID-RP2C D-Star controller I noticed an innocuous two position multi-pole PCB mount slide switch.  Each position was marked on the PCB; "analog" and "digital".    

I remember asking myself,  "Hmmm, D-Star is most definitely a digital radio mode...  I wonder what this switch does and why isn't it mentioned in the ID-RP2C user manual?", and then I closed the lid of the ID-RP2C, installed it in the 19" rack.  Although it did pique my curiosity the first time I saw it, I've never really given it much more thought.

There have been pictures of the interior of the ID-RP2C published on the internet for as long as the ID-RP2C has been available.  There used to be a Canadian D-Star web page that explored the interior workings of the Icom D-Star equipment.  I'm not sure who was behind it, but it was a fantastic treasure trove of technical information... but there was nothing on the digital/analog switch in the ID-RP2C.  I don't think I have ever read anything about the Analog/Digital switch in any of the D-Star forums or mailing lists I subscribe to, nor heard any discussion on-air about it.  Very intriguing!

Time now to jump forward to the present... this week I started thinking about the Analog/Digital switch again and looked through the ID-RP2C Service Manual, searching for info on the switch.  I found the section of schematic that showed S2, the strange Digital/Analog switch.  

S2 switches the data lines (RD, RC, RE, TD, TC & TE) normally going to/from IC17 to the fourth RJ45 socket (looking at the back of the ID-RP2C) to an 8 way internal socket labelled J25, mounted right next to S2. The data line designations on J25 are suffixed with the letter A... maybe for Analog??

 

At that moment the proverbial light bulb lit up above my head! A few years ago, Satoshi Yasuda 7M3TJZ (creator of the original D-Star Node Adapter/GMSK Hot Spot modem board), quietly added a single page .PDF document to the download section of his website.  Entitled shogen_4_2_8.pdf, it is an English translation of a previously unseen section of the original Japanese D-Star protocol specification document.  This section does not appear in the familiar English protocol document, shogen.pdf.

**Update** The Japanese language D-Star specification DOES show section 4.2.8.

Section 4.2.8 of the D-Star spec describes the operation of an Analog Bridge, an interface that uses an AMBE vocoder to "bridge" the digital D-Star system and an analog FM repeater. 

While it is an assumption, I'm convinced that the Analog/Digital switch, the J25 header and J24 power socket has something to do with section 4.2.8 of the D-Star specification and the operation of an Analog Bridge, linking the D-Star network to a traditional FM repeater!  There is most definitely enough space and threaded mounting posts inside the ID-RP2C for an additional PCB. There is also a blanked off cutout on the rear panel... possibly where the connection to the FM repeater would be.

 

J24 is not mentioned in the service manual, block diagram or circuit description.  But it IS in the schematic and PCB overlay diagram. J24 is connected to the 12V DC input, perfect for running an add on board.

Reading section 4.2.8, D-Star header information is transmitted on FM using 1200bps MSK. This header is identical to the traditional D-Star header transmitted by D-Star radios. 

An MSK modem and other supporting hardware would be required on the users FM radio to en/decode the D-Star header information. When the "Enhanced Analog" D-Star repeater transmits in response to an incoming DV stream on the internet connection, it would transmit the short MSK D-Star header and then the AMBE2020 vocoder would turn the DV voice packets into audio to be transmitted over FM. 

When transmitting back to the repeater, a users FM radio would send a brief MSK D-Star header for the MSK modem equipped Analog Bridge in the ID-RP2C to decode. The Analog Bridge would then encode the received FM audio with the AMBE2020 vocoder and send it via the Icom RS-RP2C gateway software as a normal D-Star DV stream. 

The MSK header data bursts would probably sound a little like MDC1200 used on commercial repeater networks.

I don't think the Analog Bridge board would need to have two AMBE chips, the FM repeater function would work through a conventional audio link between TX and RX. It would be pointless to encode AMBE audio from FM and then immediately decode it to be played back over the repeaters transmitter in FM.

Of course it is all well and good to have an Analog Bridge at the D-Star Gateway end, but you also need user radios that can generate the 1200 baud MSK D-Star header information... and these just do not exist! Icom obviously thought about D-Star specification section 4.2.8 enough to include S2, J25 and J24 on the ID-RP2C PCB, but that seems to be as far as it progressed.  Other than what can be found on the PCB overlay and schematic diagrams, there is NO mention of S2, J25 and J24 in either the ID-RP2C User or Service Manual... or indeed anywhere on the internet.

One advantage of this Analog Bridge system would be that ANYONE can listen to this enhanced FM repeater and be able to hear what is going on, even without having the ability to transmit the special MSK D-Star header data.  Of course they would not be able to communicate back through the D-Star Gateway without the ability to transmit the MSK D-Star header.

Shogen 4.2.8 does mention an "adaptor of analog FM rig" so in addition to a D-Star MSK header enhanced FM rig, there may have had been external MSK modem/display designed that could be added to any radio... maybe in the form of a "smart" microphone?  But unless someone from Icom Japan or the JARL D-Star Working Group discloses the original plans, I guess it's all speculation!

Amazing to think that analog FM cross connectivity is in the D-Star specification!  The Japanese language D-Star document I have has 50 pages!!  Shogen.pdf only has 12.  I wonder what else in the Japanese document hasn't been translated into English?

Sunday
Apr212013

GMSK modems for Raspberry Pi and Arduino

I received a very interesting email from Jim KI6ZUM this evening.  

Some exciting new prototype GMSK modem boards were shown at the PapaSys luncheon in San Diego.

One modem board is designed to plug into a Raspberry Pi's GPIO socket and the other is an Arduino shield. Both boards will provide yet another option for D-Star enthusiasts using the open source G4KLX ircDDB Gateway and Repeater software.  

Both the hardware design and software that will power these boards are open source.  The schematics are available from Jim KI6ZUM's web page, PCB design files will be available when the final layout is done and the code will be publicly available on a git server.

 

 

Until now the G4KLX Repeater software supported the traditional "DV Node Adapter" GMSK boards from Satoshi/Dutch*Star/MoenComm, the DV-RPTR Board, DVAP Dongle, the G4KLX software modem and even Icom repeater equipment... now there are two more options!!

The Arduino + GMSK modem shield will be able to emulate both a DVAP Dongle and a DV-RPTR board and will connect via USB to a Raspberry Pi (or other computer) running the G4KLX ircDDB Gateway software. It may be possible that this combination can be used with other software that uses the DVAP Dongle and DV-RPTR board.

The Raspberry Pi GMSK Modem board needs only a suitable N-FM radio .. add TWO radios and you get a D-Star repeater...add an internet connection for a fully functioning D-Star gateway, either simplex or full duplex!  This boards CMX589 GMSK modem connects directly to the GPIO socket.  In other USB connected GMSK DV Node Adapter boards (eg. from Satoshi, Dutch*Star, MoenComm), there is an onboard PIC with firmware that controls the modem chip and performs USB I/O functions.

Further information on these boards can be found on Jim's web page.

http://ki6zum.com/dstar/dv_overview.htm