Equipment For Federal Monitoring

[JASII]

I am just curious what equipment people like to use for federal monitoring and what features your radio(s) have that are most helpful. I have two radios. They are:

-Uniden Bearcat BCD996T

-GRE PSR-500

When doing some listening recently I decided that a couple of differences between the two really stood out in my mind between the two of them. The Uniden Bearcat BCD996T has audio mute when encrypted P25 transmissions are received. I find that to be very nice when monitoring. On the other hand the GRE PSR-500 has the ability to decode NAC codes and I really like that. My hope is that Uniden adds NAC decode and GRE adds audio mute on P25 encrypted audio, but that is probably wishful thinking on my part.

I know that Icom's IC-R2500 with the optional UT-122 will decode P-25 modulation. Does anybody know if it has audio mute when receiving encrypted audio or if it decodes NAC codes?

It looks like both the WiNRADiO WR-G305e and WR-G305i with the optional APCO P25 Decoder Plug-in will decode P25. I can't tell from their web page if it can be configured to mute encrypted audio, however.

I also know that the AOR ARD25 can be used with AOR AR-ONE, the AR8600 series and AR5000 series, but I don't think that it displays the NAC code or mutes the encrypted audio.

Is anybody here using commercial gear for P-25 monitoring? If so, can they be configured to mute encrypted audio? (I assume that none of them display NAC codes, but who knows.)

 

[naSTI]

I know that Icom's IC-R2500 with the optional UT-122 will decode P-25 modulation. Does anybody know if it has audio mute when receiving encrypted audio or if it decodes NAC codes?

- Yes the 2500 will completely mute the audio and just show the busy "light" in software. But if you are the kind that enjoys scrambled eggs, you can use the MON feature and the 2500 will unmute the mess.

- I can't comment on the WR, but of the rest of the bunch you mentioned, the PSR is the only one that does not mute.

- Most P25 commercial gear will always mute and only show a busy light if not equipped with the right key.

 

[mancow]

I would go with the PSR500. It's much more sensitive, has better decode audio, scans and searches much faster and has NAC capability.

 

[naSTI]

I would go with the PSR500. It's much more sensitive, has better decode audio, scans and searches much faster and has NAC capability.

I cannot argue with that. I own one!

BEWARE: As you've probably read, the receiver is HOT HOT HOT! Its fantastic sensitivity is severely hampered by its rediculous lack of selectivity. The PSR-500 was meant to be run with a rubber-duck.. ANY near-field transmissions or even moderate-strength adjacent channel signals render the radio almost deaf on the 50-174 Mhz range.

If you mainly use it for UHF/SHF this tends to be less of a problem.

The PSR-500's features are matched by no other scanner in its price range, but my two complaints are the selectivity and the user interface is crap and way too antiquated compared to the Uniden (however, if you're used to PRO series Radio Shack scanners, then you'll feel right at home).

Enough about the hardware.. go monitor.

 

[Mike_G_D]

Psr500

Actually, selectivity-wise, the PSR500 isn't too bad, at least relative to most other consumer scanners and especially if you engage the NFM filter.

In RF engineering referring to receiver selectivity usually means referring to the IF selectivity which is related to adjacent channel rejection (roughly how well the receiver attenuates signals within +/- x or xx KHz or so from the desired center). In this respect, as I said, I don't perceive the PSR500 to be too bad - in fact it's better than most though I do not currently have the equipment to measure it at my disposal I can pretty much tell by listening experience.

Now where the PSR500 DOES have problems is in front end overload and intermodulation rejection (IMD)! In this respect it could seriously stand improvement though, again, most consumer scanners are not well designed in this area. This has to do with how well the scanner is able to receive on channel while in the presence of in-band relatively strong interferers (by in-band I mean within the passband of the front end filter and not the IF filter as in the selectivity characteristic described above). All receivers have a point at which a strong enough in band signal or number of signals will cause problems. Front end overload typically refers to "desense" wherein strong in-band signals can cause the receiver to become very insensitive on the desired frequency. This is usually caused by the action of the internal RF automatic gain control being triggered to reduce gain by the presence of off channel but in-band strong interferers. It also often, and I am not sure correctly, refers to the rise in noise floor on channel and the appearance of off channel but in-band (and sometimes out of band, if bad enough) signals on the desired channel. The later is more related to the non-linear mixing components caused by the strong signals mixing with each other in just the right way to cause the issues described.

In the PSR500's case, based on my usage, I perceive it to be suffering substantially from bad IMD and not necessarily pure desense as I note on channel interference obviously caused by strong IM products in or near the passband.

Wideband receivers (those designed to work over a very large range of frequencies such as most scanners) are particularly hard to design in this respect without resorting to multiple switched front end bandpass filters. That would get very expensive in a consumer scanner, probably to the point of making it cost-prohibitive in a consumer market sense. Nevertheless, there are things you can do to minimize the problems including picking the receiver's internal superheterodyne frequency plan carefully, using high quality components with the active ones having good linearity over the largest signal strength range possible and the passive ones having good tolerances and Quality Factors where applicable and using good internal shielding and well isolated and matched stages is also a must. Some of the latter, I think, is where the PSR500 is lacking, unfortunately.

I have not owned one of the newer Unidens but, based on what I have read, I think they have overall better designed front ends though they are certainly not perfect. Most non-RF engineering people think that receiver sensitivity is the end-all-be-all of receiver quality and that a very sensitive receiver is just inherently prone to overload problems. Both assumptions are incorrect. There is so much more to receiver quality than sensitivity and a well designed receiver can have excellent sensitivity as well as excel in those other areas. But, again, cost will be an issue.

Anyway, again, selectivity-wise, I don't perceive the 500 to be that bad but the front end...that's definitely another matter!

-Mike

 

[JASII]

I am resurrecting my own thread. Now that the Uniden Bearcat BCD396XT has been out for a while now, I am curious how many people have this and are using it for federal monitoring, particularly P25 conventional. I still have a GRE PSR500 and I like that it displays NAC codes, but it does NOT have mute on encrypted audio. Conversely, I have a Uniden Bearcat BCD996T in the house, which does have mute on encrypted audio, but does NOT have NAC decode. Considering that the BCD396XT has both, is it now the de facto king of digital federal monitoring scanners?

 

[W6KRU]

I have 162 - 174mHz at 12.5 steps w/digital only modulation and NAC search programmed in one of the systems on my XT and it works well. The huge memory on the XT handles a system like that with only a couple of % added. The logging is the tough part right now as Proscan is the only thing that will log the XT.

 

[JASII]

Do you get any inter-modulation when searching in that manner?

 

[W6KRU]

Do you get any inter-modulation when searching in that manner?

i don't think I've heard a single instance of intermod. but I only look for digital mod. There are way too many mexican transmissions to use this method on analog.

 

[SOFA_KING]

I have been leaning on GRE to add the P25 Encryption Mute feature big time, and may have ruffled some feathers in the process (what else is new, right? ). Several of us have heard that a new firmware release is in the works. This has been known for a while. I wonder if it is taking so long because of the more complicated upgrade (that has been noted by Don S). They did not promise to add it, but did not rule it out either. I think they know they dropped the ball on the mute/mask feature and are loosing market share because of it. How may people waited for the 396XT because of that feature along with NAC? I really hope they do add it, and maybe even MDC1200 mute/mask. Even though I love my GRE (with the added FM broadcast filter in the antenna line) I am holding out on buying any more, like a PRO-106, until they add the mute feature. It would be nice to have one to scan the locals and one to search full-time.

Phil

 

[WayneH]

I can't speak for the 396XT (and my 396T is a PITA for searching Fed VHF) but I currently use my GRE, along with Phil's excellent G Band search config, to continually log P25 (with WIN500). I have some decent noise with my outside setup so once and a while I get falses just because of the certain harsh spikes in noise that happen once and a while.

Since adding an ICOM to my collection I can search Federal VHF with equal to or better sensitivity than the GRE and no RFI, intermod, etc. And it supports searching strictly in P25 mode. You get to log P25 conventional talkgroups and radio IDs. Stupidly there is no NAC search/decode though, and hence my use of the GRE.

If you're serious about Federal searching you need a quality "communications receiver" which GRE and Uniden do not currently manufacture. You lose a few frills but the receiver makes up for it.