ARD25 Data Output

[blantonl]

Interestingly I saw in Monitoring Times the advertisement for the new ARD25 - does anyone know what "data output" comes out of the RS-232 port on this thing?

 

[KC1UA]

I was hoping it was a way to flash an update into it for "future modes". After all it does say "Multimode Data Receiver" on it. The original intent of this device (when it was in a different box and known as the ARD5000) was for multiple mode capability, starting with APCO-25. Perhaps that's the thinking here as well. I can't imagine what data one would extract from this device unless it can act as a dataslicer or something along those lines.

 

[KC1UA]

Here is some very interesting and potentially good news, cut from the SCAN-L mailing list, regarding the ARD25. I pasted it into Notepad and uploaded it to my site.

http://www.scanmassachusetts.net/misc/ARD25.txt

Despite the price I picked one up from Lentini Communications and am using it with an also recently acquired AOR AR5000 receiver. Nice combination with a few quirks that I'll explain when I have a little more time.

The news from SCAN-L should prove quite interesting to folks with discriminator taps. If AOR will drop the price of this device somewhat they could potentially sell a lot of them.

 

[blantonl]

Here is the message directly for the benefit of the forum users:

Date: Tue, 15 Jun 2004 14:17:24 -0400
From: Steven Donnell WA1YKL <radiodf@RCN.COM>
Subject: New Project 25 Decoder

For the past couple weeks we have been playing w/ the ARD25 (P25)digital
decoder from AOR. I am very pleased to see a manufacturer produce a
standalone decoder for Prpject 25 communications. This avoids(in part)
having to pay the hefty price tag for a full P25 scanner, particularly
in areas such as NH here where most P25 systems operate in a non trunked
mode. The ARD25 is designed primarily to interface w/ certain AOR and
Icom scanner/receivers that include a 10.7 MHz IF ouput connection. We
initally tested the ARD25 w/ our IC-R7000 and saw that it decoded P25
signals from NH State Police and other local Depts quite easily.

I wanted to see if it could be interfaced to other receivers that were
designed w/ a 10.7 MHz IF. We initally tried our old Regency Turboscan
by adding a tap at the ouput of the 1st Mixer stage, and it connecting
to the input of the ARD. At first we could not get the ARD25 to decode
anything. Then we realised what the problem was: The "polarity" of the
P25 data was inverted due to the IF conversion scheme used in the TS2.
We sound this out when we programmed a frequency 172.800 MHZ into the
TS2 so as to have it receive what we had been trying to get previosuly
on 151.400 MHz(NHSP) as an "image" frequency. This worked because it
placed the scanner's Local Oscillator above(instead of below) the
intended receive freq, and permitted the demodulated P25 voice "data" to
have the correct polarity orientation. We further reasoned that this
same effect could be accomplished by changing a 10.245 MHz IF conversion
crystal, used in the ARD25 to convert the 10.7 Mhz signal down to 455
KHz, to a lesser used 11.155 MHz crystal to produce the same 10.7 to
455 IF conversion, but produce demodulated data w/ the correct
"polarity".

Since the ARD includes a serial data port that permits a PC running
Hyperterminal to communciate w/ the ARD25, as well as a means to display
decoded Talk Group#s and even Unit ANI IDs, I wondered if there was an
easier way to get the correct data polarity by way of a software
command. An inquiry to AOR Cusomter Support revealed that this was
indeed possible. However the information they initally provided wasnt
complete and it took us a great deal of experimenting in order to
finally get this figured out. In the course of doing this we uncovered a
number of additional commands that can be set for different purposes.
For instance sending the command ADC will produce a short listing of
about dozen function/settings the ARD25 can be commanded to do. Some
commands, such as the data polarity setting require a certain extra
trick in order for it to actaully take effect... Another useful command
the ARD25 can be set for is ADA ON/OFF. This selects if you want it to
pass analog signals as well as digital ones. This is a feature none of
the current crop of P25 scanners are capible of. It would seem that AOR
seriously faulted here in terms of what they did not bother to inlcude
in the manual for the ARD25. Nor does there seem to be any reason as to
why AOR uses a male DB9 connector on the ARD25, which requires the use
of a female/female adapator or cable in order to communicate w/ it via a
PC.

Always wanting to go further we also wondered if there was a means to
interface the ARD25 to other receivers(that dont use a 10.7 IF) by way
of simply providing a "baseband" data connection from a receiver. After
much careful experiementation we found that it was indeed possible to
connect the Discriminator signal from nearly any scanner, into the
ARD25, substituting an external signal for that of the ARDs own IF
demodulator output. So far we have successfully tested the ARD w/ by
using the discriminator signal from other scanners such as the BC760,
245, 780 and 9000. This discovery makes the ARD25 a far more
universal/flexible platform for decoding P25 transmissions than what
AOR seems to be interested in marketing this product for. We plan on
having a complete writeup explaining these hidden features as well as
the hardware mods we noted, along we installation details for several
popualr scanners in the coming months if there is adaquate interst in
this area.

Steve DE WA1YKL

 

[blantonl]

There was also a big debate running on SCAN-L about the usefulness of this piece of equipment.

I'm inclined to agree with many of the posters that this isn't that useful for most people. I think you'll be better off purchasing a PRO-96, unless this add on box included things like a s.w dev toolkit, or flash updates for other digital voice options.

 

[KC1UA]

I agree with that as well, unless AOR reduces the price and the information above is clearly and concisely documented for the mainstream, it likely won't sell much.

As you've possibly read elsewhere, I'm a big fan of DX'ing, so the ARD25 intrigued me as an add-on to the AR5000. It immediately worked for me last night during a reasonably good tropo band opening in my area. Audio seems crisp and clear, not muddy as I've found the Unidens to be sometimes. Audio sounds more like the PRO-96 from my brief experience with it.

I continue to hold hope that this device, with the label "Multimode Data Receiver" on the front, will do just that, be flashable and handle multi-modes. With gentlemen like Steve digging into the potential of such a device, I'm hoping that it might become a very interesting, unique, and versatile piece of gear. What is really surprising is that AOR did not advertise it to work with a discriminator tap, when from what Steve describes, it apparently clearly does. One would think that they could advertise that, lower its price, and sell a lot more of them. Time will tell, but maybe its entry into the digital game is too little too late for the mainstream of scannists.

 

[SCPD]

Apco25 ARD25 decoder

Just been reading the posts on this decoder with interest. I don't have an AOR receiver with a 10.7IF output. But I have a couple of questions maybe someone can answer, if they can test this device.
OK so it works from a discriminator tap, but how well? How good is the audio quality compared to one hooked up to a 10.7IF?
Also if you hook this up to a trunk tracker, does it decode APCO25 talk group voice as well? How about on 9600 baud trunk systems (not that this bothers me).

Dave

 

[kg4icg]

It does not work from a discriminator tap. 10.7 if and discriminator tap are totally different animals. Discriminator tap is pulling unfiltered audio out at a certain point. 10.7IF is pulling a signal from the reference oscillator of the receiver. The 10.7mhz IF from high end receiver's are used to hook up spectrum analyzer's and other lab equipment for testing signal quality. I guess by me saying please do not confuse a 10.7 mhz IF with a discriminator tap will get ignored again.

R Collins

it looks like someone is converting the audio tap into a reference tap by adding part's good luck with the soldering.

 

[KC1UA]

I'm not sure what you're reading, but from what I'm reading it certainly looks like Steve was able to use a "standard" discriminator output of various radios to make the ARD25 work. I either missed it or there was nothing there regarding having to do anything above and beyond using a discriminator tap. I am not schooled in electronics as you might be, but from what I read that's what I gathered. I DO know the difference between a 10.7 MHz IF output and a discriminator, however. :wink:

I'll bet there will be info aplenty down the road and that this device will do quite a bit. I guess we'll have to wait and see. I'm pleased to see a "third alternative" although as mentioned time and again AOR needs to reconsider the price in a big way.

 

[rdale]

"Another useful command
the ARD25 can be set for is ADA ON/OFF. This selects if you want it to
pass analog signals as well as digital ones. This is a feature none of
the current crop of P25 scanners are capible of."

I don't understand this... Is he (incorrectly) saying that current digital scanners don't work with analog systems? Or does the ARD block analog unless this trick code is used?

 

[KC1UA]

I think what he means, Rob, is a problem that does tend to plague us on the current scanners with conventional APCO-25. As the frequency must be programmed in FM mode (no PL/DPL info as it won't work) in addition to the actual P25 traffic we're trying to listen to, we'll hear any analog traffic on the same frequency within our range. It sounds like this command gives the option for the ARD25 to not pass anything but digital traffic. I doubt it would make much difference on trunked systems (providing the following radio was feeding the ARD25 of course) but on conventional frequencies it could be very helpful.

I think... :roll:

 

[AZScanner]

I think what he means, Rob, is a problem that does tend to plague us on the current scanners with conventional APCO-25. As the frequency must be programmed in FM mode (no PL/DPL info as it won't work) in addition to the actual P25 traffic we're trying to listen to, we'll hear any analog traffic on the same frequency within our range. It sounds like this command gives the option for the ARD25 to not pass anything but digital traffic. I doubt it would make much difference on trunked systems (providing the following radio was feeding the ARD25 of course) but on conventional frequencies it could be very helpful.

I think... :roll:

Scott, how does the digital only mode handle encryption? Does it still try to decode it or does it do a better job of detecting the encryption than the Unidens or GRE's?

-AZ

 

[KC1UA]

From the ARD25 manual:

"If the signal is received and the front BUSY lit, but no recovered audio is heard from the internal speaker, the received signal may be encrypted. However, it is normal for the ARD25."

I haven't had a direct experience with this yet but from the sounds of things it just simply doesn't pass the audio at all.

 

[AZScanner]

From the ARD25 manual:

"If the signal is received and the front BUSY lit, but no recovered audio is heard from the internal speaker, the received signal may be encrypted. However, it is normal for the ARD25."

I haven't had a direct experience with this yet but from the sounds of things it just simply doesn't pass the audio at all.

Ooh, nice! I wish my 250D was smart enough to do that.

-AZ