Loss of P25 after BCD536HP firmware update

[Minus1]

Anyone else with a Uniden BCD536HP suffering an almost complete loss of any P25 reception after the recent firmware update (1.06.10)?
It still picks up a signal, and detects the WACN and NAC via the new Analyze function, but reception of any actual audio is virtually non-existent!
I managed a brief burst of something once whilst messing around with the bewildering number of settings, but then nothing.
Even resorting to getting to a much better location failed to improve things. Though it did choose a lower threshold level.

Grrrrr.

[Windy_Miller]

Can't say P25 is any use to me, but have just applied the update to the 436 and agree with some of the postings on Radio Reference in that the conventional scan rate seems to have increased. Hard to tell exactly what rate its doing, but it seems to be over 100 channels a second. Hard to get an exact speed because the damned thing sometimes zips that fast through a favourites list or a system that pixels on the display don't even blink on. But on average, I would say its knocking out somewhere about 110 channels per second, and thats slewing all over the place from 27 MHz to 1300 MHz.

Not found anything else of interest in the firmware update yet.

[Minus1]

You're right about it being too fast the see what is going on! A stark contrast to my first scanner that only had 20 channels.
The only really useful thing I can see is the Analyze function which shows the "WACN" for P25 sites, just a shame I can no longer receive much audio...

This is what it reports for the USAF site at Croughton:
System ID: 0169-002
Site ID: 007
WACN: BEE00 (that translates to a 'callsign' of "0UX G", but I don't yet understand the context of that)

I did manage one brief burst of audio yesterday, using a threshold level of 6 which is lower than what I used to find best. Still experimenting though.

[Andy]

I'm fairly new to all this digital what-not. I'm getting plenty of DMR and NXDR, but so far I haven't come across any P25. I know it's a bit thin on the ground in the UK, but where can I find some? I'm in north Cheshire. Many thanks.

[Minus1]

From North Cheshire, nearest are the US bases at Croughton in Northants (417.725), Molesworth in Cambridgeshire (404.525), and Menwith Hill in North Yorks (406.325). All a bit of out of range.

I did see a report that the RAF are going to start using P25 at their stations though, and Shawbury would be in range. Not yet found any such RAF transmissions though.

I managed to catch another brief P25 burst last night, but only a few seconds.

[jhampton2000]

Even further away, and not heard in a while, but there is often quite a lot of P25 in use in the Salisbury Plain Training Areas (415-420Mhz area). HMRC use P25 too, but all encrypted, to be heard at Airports.

Anyone know if 431.500 is frequently used at Croughton? Often P25 but sometimes in the clear too.

[Andy]

Thanks chaps. That's the disadvantage of living in the NW, we are miles away from most military stuff!

[Minus1]

Thanks chaps. That's the disadvantage of living in the NW, we are miles away from most military stuff!

The Defence Bills Agency (DBA) in Liverpool (Mersey House, Drury Lane, Liverpool L2 7PX) was mentioned as using 411.2 MHz in some OFCOM report I read a while ago. I have no idea if that is still current.

[Minus1]

Even further away, and not heard in a while, but there is often quite a lot of P25 in use in the Salisbury Plain Training Areas (415-420Mhz area).

There was a P25 control signal on 416.45 MHz with an NCA of 8B8, I noticed this in the Salisbury Plain area a while ago, but picked up the NAC via lift conditions.

[zanco]

Hi, I joined this forum to be able to reply to this topic, although I have no scanner with P25 reception and no problem with a firmware update but I am interested in the P25 use in the UK.

The story is:
For the last (about) 6 months I receive every now and then a digital signal on 404.525 which seems to follow the signal strength of a launched radiosonde. I monitor these sondes on regular base but since march there appeared a digital signal, sometimes close to the launch time of Meppen in Germany but sometimes on different times. The reception is best for me with the LogPer in the direction of the UK. Being 7 km from the Northsea coast that leaves not much options over here. Yesterday evening and this morning around 02:30 UTC the signal appeared again. I catched an IQ file and did send it to my brother who had DSD running on SDRSharp, and he told me that messages like Sync:+P25p1 NAC:164 appeared.

I did not find any results on googling on the frequency 404.525 in combination with MHz but his first hit for 404.525 in combination with P25 did point to this forum, where the frequency is mentioned for an Air base and the use of P25 is mentioned. Could it be possible that digital radiosondes are being launched from Molesworth ? I have an IQ file from the centerfrequency which plays back great on SDRConsole and without tuning and forward possibilities (first 4 minutes of the signal are quite noisy and almost invisible on SDR#) on my dropbox account, the file is about 200 MB

https://www.dropbox.com/s/fxa3xa776yncw ... 0.wav?dl=0

The signals looks like this:

404_525.JPG

And played back in 5 minute steps you can see the declination of the signal strenght. (I mean that the signal strenght gets lower and lower, don't know if declination is the good word here)

404_525_signaal.JPG

I will review my recordings to see if there is a regularly interval in these signals.

There is one thing that also has to be mentioned: As soon as the signal on 404.525 reaches it's max short transmissions appear on 404.825 and 404.875 which look the same. Had no time to check if DSD recognizes them also as P25.

Kind regards,
Ben

[Minus1]

404.525 is the P25 control channel from the USAF base at RAF Molesworth. It transmits continuously, so is a good dx indicator if it is just outside your normal receiving range. The mast is at 52.383111°N 0.418889°W

The 'Talk" channels (I'm not sure what the proper name is) are on:
404.825
404.875
405.1
These switch on automatically depending upon what the radio traffic is.


This is system "169-2", site number 4, WCAN "BEE00", NAC164.
I've seen NAC293 appear a few times on 405.1, not sure why that is.
I haven't been able to find the corresponding mobile input frequencies yet, but did detect something on 399.375 which I didn't have time to check.
This would tie in with the signal-defined P25 band plan of 380MHz to 406MHz.
All the other P25 signals I've found in the UK are above 406MHz.

Talk Group "46118" is the Fire Dept.

I've no idea if RadioSondes are launched from Molesworth, but the frequency you mention is not from a balloon, even though the band is used by balloons elsewhere in the UK.
Other than meteorological balloons, Molesworth is the only military facility that I am aware of in the UK, that uses the 401-406 band.
I suspect the radio propagation happened to be just right for the signal to reach you.

[zanco]

Hi,

Thanks a lot for your detailed reply. All the pieces of my puzzle came together, it also explains the strength of the talk channels following the control channel strength on 404.525 becaues it's all about DX. It also explains the quite random timing and duration of the appearing from the signal. Sometimes just 15 minutes and sometimes about 2 hours.

DX distance is 318 km The antenna mast shows up nicely on Google Maps.
Do you happen to know the output power for the control channel ?

Kind regards,

Ben - PE2BZ

[Minus1]

I don't know the power, but obviously a lot more than is used by RAF stations in the UK, as the P25 control channels can easily be picked up at distances of 30 miles whilst in the car without trying very hard. All the masts seem to be comparively high, which doubtless helps.

[zanco]

Thanks.

On 401.350 (with good conditions) there is another P25 control channel which also seems to come from the UK.

[bigbloke]

salisbury plain also radiate from the UK - 416.6 NAC 8B8 there is a second control channel
dont remember the frequency

Regards

BB