Search found 58 matches

by MattSR
Thu Oct 15, 2009 4:24 am
Forum: Astro DStar and other digital voice formats
Topic: amplification and p25
Replies: 6
Views: 6464

Re: amplification and p25

escomm wrote:maybe wowbagger can shine some expertise on this matter
I doubt it - everyone has summed it up pretty much already.

the TPL PA6 is the amp supplied by Motorola for XTVA installations. If Mother M reccomend it for use with XTS radios, then i'd say its a fair bet any old Class C amp will work.
by MattSR
Tue Sep 29, 2009 9:21 am
Forum: Astro DStar and other digital voice formats
Topic: ASTRO Ham Band Repeaters (NATIONWIDE LIST)
Replies: 36
Views: 37842

Re: ASTRO Ham Band Repeaters (NATIONWIDE LIST)

Please note - use 2.5khz deviation (12.5khz spacing) when setting this in your radio.
by MattSR
Tue Sep 29, 2009 9:20 am
Forum: Astro DStar and other digital voice formats
Topic: ASTRO Ham Band Repeaters (NATIONWIDE LIST)
Replies: 36
Views: 37842

Re: ASTRO Ham Band Repeaters (NATIONWIDE LIST)

VK2RCG, 438.2000 output and 432.8000 input (Note the non-standard split) with NAC of 293.

Location, Sydney Australia.

Several more P25 machines to come, ill let you know when they are up and linked.
by MattSR
Wed Sep 23, 2009 9:23 am
Forum: Astro DStar and other digital voice formats
Topic: amplification and p25
Replies: 6
Views: 6464

Re: amplification and p25

I've used a TPL PA6 on 70cm on P25. Worked really well, but I never checked the output of the amp on a service monitor or anything.
by MattSR
Fri Aug 21, 2009 9:09 am
Forum: Astro DStar and other digital voice formats
Topic: P25 repeaters
Replies: 75
Views: 65562

Re: P25 repeaters

Hehe I'm not surprised - just as the P25 CAI evolved from ASTRO VSELP, P25-KFD probably evolved from ASN legacy mode. In any case, its a very common style of interface thats been documented in many engineering textbooks since before 2 way radios started using encryption... All they're really patenti...
by MattSR
Thu Aug 20, 2009 10:30 pm
Forum: Astro DStar and other digital voice formats
Topic: P25 repeaters
Replies: 75
Views: 65562

Re: P25 repeaters

OK cool, that puts my mind at rest. I expected as much re the wide pulse/LSM/other proprietary stuff Yes - ADP algorithm isn't part of the P25 spec, so I would automatically consider that to be proprietary. Here's where it gets tricky though. the Keyfill interface/protocol *is* part of the publicly ...
by MattSR
Thu Aug 20, 2009 8:47 pm
Forum: Astro DStar and other digital voice formats
Topic: P25 repeaters
Replies: 75
Views: 65562

Re: P25 repeaters

I wouldn't be worried about number 1 - Aeroflex's framework would be vastly different and more mature than OP25/GNUradio since the latter are only part time "enthusiast" type projects. Your analyzers appear to be designed and built/coded to a spec - OP25 is more 'beta' software at this stage, and as...
by MattSR
Thu Aug 20, 2009 11:47 am
Forum: Astro DStar and other digital voice formats
Topic: P25 repeaters
Replies: 75
Views: 65562

Re: P25 repeaters

Like any software project, (especially one like OP25) this project has people with all sorts of eclectic skills.

Join the mailing list and you'll see exactly how/what I contribute. Surely your employer won't discipline you for reading up on our efforts.
by MattSR
Thu Aug 20, 2009 9:29 am
Forum: Astro DStar and other digital voice formats
Topic: P25 repeaters
Replies: 75
Views: 65562

Re: P25 repeaters

Work continues. There is now discriminator tap support, amongst other improvements. A DV Dongle AMBE decoder has been ordered and we will try feeding IMBE frames into it. Hopefully it works! The latest update enabled me to capture the following screenshots - one is an ADP tranmission, another DES-OF...
by MattSR
Thu Aug 20, 2009 9:27 am
Forum: Astro DStar and other digital voice formats
Topic: P25 repeaters
Replies: 75
Views: 65562

Re: P25 repeaters

Work continues. There is now discriminator tap support, amongst other improvements. The latest update enabled me to capture the following screenshots - one is an ADP tranmission, another DES-OFB. The Symbol scope shows the output from the C4FM demodulator. http://img.photobucket.com/albums/v105/Matt...
by MattSR
Wed Jul 22, 2009 7:51 am
Forum: Astro DStar and other digital voice formats
Topic: P25 repeaters
Replies: 75
Views: 65562

Re: P25 repeaters

OP25 will get there. Once the receive code is complete, then work will start on tx code. Cheers, Matt How are you handling the vocoding? Are you using the DVSI USB dongle, or just spacing that bit off for now? Also, are you deriving any of the parametrics on the signal, such as Mod Fidelity error o...
by MattSR
Sun Jul 05, 2009 11:02 pm
Forum: Astro DStar and other digital voice formats
Topic: P25 repeaters
Replies: 75
Views: 65562

Re: P25 repeaters

OP25 will get there. Once the receive code is complete, then work will start on tx code.

Cheers,
Matt
by MattSR
Thu Jul 02, 2009 7:34 pm
Forum: Astro DStar and other digital voice formats
Topic: P25 repeaters
Replies: 75
Views: 65562

Re: P25 repeaters

GNUradio 3.2 stable was released a few weeks ago, and OP25 is coming along nicely under the new platform. There have been a number of very interesting additions to the code, and it is expected that over the next month or so some more features will be added. I requested some additions to the GUI that...
by MattSR
Tue Nov 18, 2008 1:13 am
Forum: Astro DStar and other digital voice formats
Topic: P25 repeaters
Replies: 75
Views: 65562

Re: P25 repeaters

Ahh fuck. can someone fix my quote tag plz?
by MattSR
Tue Nov 18, 2008 1:12 am
Forum: Astro DStar and other digital voice formats
Topic: P25 repeaters
Replies: 75
Views: 65562

Re: P25 repeaters

I wonder if I ought to point out the DTD and RelaxNG schema for our XML logger to them - we (Aeroflex) would like to see others using that for logging. I will pass this onto the project leader.. One of the things to investigate is a C4FM modulator/RRC filter/Shaping filter/NFM modulator series of b...
by MattSR
Sun Nov 02, 2008 5:30 pm
Forum: Astro DStar and other digital voice formats
Topic: P25 repeaters
Replies: 75
Views: 65562

Re: P25 repeaters

Wowbagger wrote:but there is no way to implement IMBE without infringing upon DVSI's patents..
A hardware dongle with an appropriately licensed and purchased codec chip would be OK.
by MattSR
Sun Nov 02, 2008 5:28 pm
Forum: Astro DStar and other digital voice formats
Topic: P25 repeaters
Replies: 75
Views: 65562

Re: P25 repeaters

better than that AIM thinger :(
by MattSR
Sun Nov 02, 2008 6:20 am
Forum: Astro DStar and other digital voice formats
Topic: P25 repeaters
Replies: 75
Views: 65562

Re: P25 repeaters

Thats cool, but why?

and why arent you on MSN anymore?
by MattSR
Sun Nov 02, 2008 12:09 am
Forum: Astro DStar and other digital voice formats
Topic: P25 repeaters
Replies: 75
Views: 65562

Re: P25 repeaters

Stop playing with the GSM mobile phone networks matt! Dont u know thats illegal :wacker:
by MattSR
Sat Nov 01, 2008 11:29 pm
Forum: Astro DStar and other digital voice formats
Topic: P25 repeaters
Replies: 75
Views: 65562

Re: P25 repeaters

Correct - clock recovery etc is done by the CML chip where as the P25 stuff (NAC, error correction) would be done by the Atmel. The pdfs from CML explain it better than I can (just delete the codec and mic/speaker bits of the block diagram - thats only used for voice which wouldn't be required for a...
by MattSR
Sat Nov 01, 2008 9:19 pm
Forum: Astro DStar and other digital voice formats
Topic: P25 repeaters
Replies: 75
Views: 65562

Re: P25 repeaters

These chips from CML micros could be the basis for a simple P25 machine. Couple with with an atmel ATMega16 to run the show and bobs your uncle goto http://www.cmlmicro.com/products/index.asp?searchvalue=C4FM&setindex=true and click on the C4FM Modem function. ATmega16 can do SPI which is the bus u...
by MattSR
Sat Nov 01, 2008 7:28 pm
Forum: Astro DStar and other digital voice formats
Topic: P25 repeaters
Replies: 75
Views: 65562

Re: P25 repeaters

USRP isn't needed - GNUradio can run off a discriminator tap (apprently) I'm having a hell of a time trying to get it to compile and run properly.. its a fairly big, complex, fragile thing by the looks of it... escomm - why the soapbox? we're only throwing ieads around to try and get the creative ju...
by MattSR
Fri Oct 31, 2008 9:02 pm
Forum: Astro DStar and other digital voice formats
Topic: P25 repeaters
Replies: 75
Views: 65562

Re: P25 repeaters

Long time no speak.

Funny you should mention OP25 - I've been playing with it for about a week now - the wireshark extensions look quite useful. Next step is to build a dedicated linux machine and move it out of VMware.
by MattSR
Tue Oct 28, 2008 11:34 pm
Forum: Astro DStar and other digital voice formats
Topic: P25 repeaters
Replies: 75
Views: 65562

Re: P25 repeaters

P25 uses bitrate of 9.6kbps (4800 bits per second signalling rate @ 2 bits per symbol) The chips (when loaded with the correct image) have been specifically designed for a P25 application. They even automatically detect and insert the P25 frame sync for you. Have a look at CML micros documentation o...
by MattSR
Thu Aug 07, 2008 8:18 pm
Forum: Astro DStar and other digital voice formats
Topic: P25 repeaters
Replies: 75
Views: 65562

Re: P25 repeaters

Hardest thing I came across was the sale poons at CML. Al I wanted was some samples of the chips and the data sheets/SPI instruction sets. Do you thnk they would sell them to me? No way.. They wanted to see my support structure, intended customer base, production volumes, blah blah... when I tried e...
by MattSR
Thu Aug 07, 2008 6:45 pm
Forum: Astro DStar and other digital voice formats
Topic: P25 repeaters
Replies: 75
Views: 65562

Re: P25 repeaters

These chips from CML micros could be the basis for a simple P25 machine. Couple with with an atmel ATMega16 to run the show and bobs your uncle goto http://www.cmlmicro.com/products/index.asp?searchvalue=C4FM&setindex=true and click on the C4FM Modem function. ATmega16 can do SPI which is the bus us...
by MattSR
Tue Jan 08, 2008 9:40 am
Forum: Astro DStar and other digital voice formats
Topic: Encryption on P25
Replies: 89
Views: 64110

Re: Encryption on P25

It's mainly the weather. Australia's is pretty close to home, yet yours is, well.. not for me. :ve4uo: Australia's a big place ;) Yeah, we even have a missile range bigger than England :baby: And its probably just as radioactive as the UK is too (Sellafield/Windscale disaster) :wacker: :wacker:
by MattSR
Sun Oct 21, 2007 11:19 pm
Forum: Astro DStar and other digital voice formats
Topic: XTS3000 KVL cable/adaptor
Replies: 6
Views: 5107

Or you could do it the hard-but-cheap way, and build your own from a junked Jedi speaker mic connector. The board doesn't have spaces for the keyloading pins, though, so you'll have to etch your own or do something :vestman: -grade with glue and pins or whatever. Building a Saber keyloading cable i...
by MattSR
Mon Sep 17, 2007 12:37 am
Forum: Astro DStar and other digital voice formats
Topic: Saber Keyloader
Replies: 13
Views: 7920

You can upgrade AX and BX to DX as well if you get an upgrade SRAM chip
by MattSR
Mon Sep 03, 2007 1:10 am
Forum: Astro DStar and other digital voice formats
Topic: Apco technical questions
Replies: 19
Views: 10661

One chipset.

The smarts for decoding the different protocols (P25, DSTAR etc) are all in the host microcontroller.

Matt
by MattSR
Sat Sep 01, 2007 5:19 am
Forum: Astro DStar and other digital voice formats
Topic: XTS2500 Type I UCM support
Replies: 5
Views: 3901

Didn't think of that - at least that way its certified too..
by MattSR
Sat Sep 01, 2007 4:16 am
Forum: Astro DStar and other digital voice formats
Topic: XTS2500 Type I UCM support
Replies: 5
Views: 3901

OK, i've done some more investigation and it appears that XTS2500 Type I support is the same as the 5k - it requires some physical modifications in the form of removing a few zero ohm resistors.. etc etc. Maybe a specific firmware version is also required too? Alex - I must disagree with your point....
by MattSR
Sat Sep 01, 2007 2:42 am
Forum: Astro DStar and other digital voice formats
Topic: Apco technical questions
Replies: 19
Views: 10661

Also from the glossary inside the P25 training manual posted above:-
AMBE+2™
Abbreviation for “Advanced Multi Band
Excitation”. An enhanced Vocoder that
is backwards compatible with IMBE™.
by MattSR
Sat Sep 01, 2007 2:38 am
Forum: Astro DStar and other digital voice formats
Topic: Apco technical questions
Replies: 19
Views: 10661

From DVSI's website - http://www.dvsinc.com/products/VC-55.htm provides a number of other vocoder advancements while remaining fully interoperable with the existing APCO Project 25 vocoder standard (TIA-102BABA) I have read other references on the net but nothing from an offical source. Given the P2...
by MattSR
Fri Aug 31, 2007 9:23 pm
Forum: Astro DStar and other digital voice formats
Topic: Apco technical questions
Replies: 19
Views: 10661

The vocoder isn't a problem, you can buy a DSP preloaded with IMBE from DVSI for about $20 a pop. Drop it on a board with a serial codec and you're laughing. Negative ghost rider...Any plain jane hobbiest cannot get their hands on the IMBE codec info. Per DVSI it is the firmware CODE for the codec ...