WBFM in milair band

[RichardKramer]

I monitor the satcom band from 240 - 270MHz every day at some point. So I am familiar with what tx are in that range. Since Nov 2023 I've been receiving wbfm transmissions in the 240 - 300MHz range. These transmissions are not pirate satellites in the fm mode; they are local and consist of phone calls, music playing. I'm pretty sure they are coming from vehicles as the transmissions refer to stopping for gas, getting groceries, picking someone up for work, etc. They are brief from a few seconds to sometimes several minutes. The busiest times I rx them is at the change of work shifts in the am and pm hours. I know bluetooth operates in the 2.4GHz range and are digital; but I have heard "bluetooth connected on a lot of the transmissions". If you listen in the fm mode the transmissions are garbled. Does anyone know if there are analog bluetooth units that people would use in their vehicles that tx in this range?
They are not harmonics or images. I hear them on several different scanners that can rx wbfm. Everyday I can count on hearing the same frequecies being used and there are over 30 frequencies that I rx and seem to be spaced 25KHz apart. If you can rx in that band in the wbfm mode, I would like to hear if anyone else is receiving transmissions like these. I can pick them up while mobile in my suv while driving around the County here in Berks, PA. Thanks for any info you can provide on these transmissions.

 

[bearcatrp]

What radios have WBFM? Don't think I have seen that.

 

[N9JCQ]

An SDR would. Also, my Yupiteru 7100 can receive this as well. I honestly never thought to look for WBFM there before.

 

[N1XDS]

What radios have WBFM? Don't think I have seen that.

Thales military portable radios

 

[RichardKramer]

What radios have WBFM? Don't think I have seen that.

This would be a device connected in the car to the cell phone that would relay the calls to a headset or set of speakers that tx in the analog wbfm mode. All the devices I could find on the internet all seem to be the digital 2.4GHz bluetooth relays; I couldn't find anything in the specs that said wbfm analog mode. Wondering if these devices could be from China?, or another foreign Country. I also wonder when we hear the CAP pilots talk about rfi on their uhf freqs if these could be the culprit? I do hear the tx of "bluetooth connected" during some of the calls.

 

[Mike_G_D]

No analog audio in the Bluetooth spec. One thought that came to my mind was that it might be illegal export "long range cordless phones". I've seen a lot of these that, when you can find some specs on them and you do see a freq. range they often show up in parts of what we think of as the UHF mil air band. They are often advertised as very long range and can use external antennas with selling points illustrating the use of a base antenna for the base unit and mobile antennas, etc. Might be this might not be - just a thought as a possibility. If it is this then you might try DFing when you next hear them and maybe trying to find the "source base station". Anyway, just a thought.

 

[BinaryMode]

What radios have WBFM? Don't think I have seen that.

Many scanners have WFM. The P2's do for example. Even my old RadioShack Pro-2042 has WFM.

NFM: ~7.5 kHz deviation
FM: ~15 kHz deviation
FMB: ~75 kHz deviation
WFM: >100 kHz deviation

BCD325P2 - The RadioReference Wiki

wiki.radioreference.com

The tilde (~) should be replaced with the almost equals sign (≈).

 

[prcguy]

Thales military portable radios

I think the OP means +/- 75KHz deviation FM broadcast WBFM, the Thales radios can't do that.

Something to consider is a harmonic of an FM deviated signal will double the deviation on the second harmonic, triple on the third, etc, so a narrow band FM signal can be quite wide if your picking up a harmonic.

 

[dlwtrunked]

I monitor the satcom band from 240 - 270MHz every day at some point. So I am familiar with what tx are in that range. Since Nov 2023 I've been receiving wbfm transmissions in the 240 - 300MHz range. These transmissions are not pirate satellites in the fm mode; they are local and consist of phone calls, music playing. I'm pretty sure they are coming from vehicles as the transmissions refer to stopping for gas, getting groceries, picking someone up for work, etc. They are brief from a few seconds to sometimes several minutes. The busiest times I rx them is at the change of work shifts in the am and pm hours. I know bluetooth operates in the 2.4GHz range and are digital; but I have heard "bluetooth connected on a lot of the transmissions". If you listen in the fm mode the transmissions are garbled. Does anyone know if there are analog bluetooth units that people would use in their vehicles that tx in this range?
They are not harmonics or images. I hear them on several different scanners that can rx wbfm. Everyday I can count on hearing the same frequecies being used and there are over 30 frequencies that I rx and seem to be spaced 25KHz apart. If you can rx in that band in the wbfm mode, I would like to hear if anyone else is receiving transmissions like these. I can pick them up while mobile in my suv while driving around the County here in Berks, PA. Thanks for any info you can provide on these transmissions.

Look at 1/3 the frequency. Devices to play audio in the FM band for car radios are common. The third harmonic would be you your frequency range. Because of the discussions you heard, I would almost bet on it.

 

[Wilrobnson]

Thales military portable radios

There also used to be some of the overseas-market portables running 325-327mhz WBFM. I think they were from the Philippines. Also, a friend who was recently in Thailand was making jokes about bringing home some of their "Red" radios, which are basically FRS radios in the 245mhz band.

 

[bearcatrp]

Many scanners have WFM. The P2's do for example. Even my old RadioShack Pro-2042 has WFM.

NFM: ~7.5 kHz deviation
FM: ~15 kHz deviation
FMB: ~75 kHz deviation
WFM: >100 kHz deviation

BCD325P2 - The RadioReference Wiki

wiki.radioreference.com

The tilde (~) should be replaced with the almost equals sign (≈).

Did not know this. Thanks for the update. Am assuming the scanner will not auto switch since that particular band is set with WFM, correct?

 

[prcguy]

BinaryMode said:
Many scanners have WFM. The P2's do for example. Even my old RadioShack Pro-2042 has WFM.

NFM: ~7.5 kHz deviation
FM: ~15 kHz deviation
FMB: ~75 kHz deviation
WFM: >100 kHz deviation

That looks like a scanners IF filter specs. Actual radio specs would be a maximum of +/- 2.5KHz deviation for narrow band, +/- 5KHz for FM, +/- 25KHz for old analog TV FM deviation, +/- 75KHz for broadcast (wideband) FM.

 

[RFI-EMI-GUY]

These old analog ALTAI mobile phones as used in Russia uplink in the 330 MHz range and thus get relayed to the 260 MHz range of the USDOD Milsats. That the US has not filtered them nor ever complained, in decades, is probably because of the valuable ELINT and HUMINT they produce daily. I have monitored these in past and it is quite interesting indeed.

Altai 3M - Mobilecollectors.net

 

[IC-R20]

What radios have WBFM? Don't think I have seen that.

Long range cordless phones. I had a 5 watt set when I lived in Japan long ago. You can still get Alcon ones today and they occasionally pop up in the USA. I found one in 2016 when helping a friend clean out a single story apartment for contract. Was connected to a rooftop antenna.

They’re mainly used outside the USA and have made base stations and mobiles that run up to 40 watts. The mobiles have a regular handset and are basically like the carphones in the 70s and 80s. I‘ve also seen point to point sets where they come with yagis so you can extend a line out to a remote building or property. They duplex 200 and 300 MHz range usually being close to the middle of each somewhere.

https://manualzz.com/doc/57847118/alcon-ct-88-owner-s-guide

 

[RFI-EMI-GUY]

UHF SATCOM Downlinks Receivable in North America

 

[RichardKramer]

Look at 1/3 the frequency. Devices to play audio in the FM band for car radios are common. The third harmonic would be you your frequency range. Because of the discussions you heard, I would almost bet on it.

I found my older, 15yrs (scosche) fm tx for the car or portable use; tried it in the house with a scanner tuned to the wx ch. You're right 3rd harmonic, although about 10 yards is the max to rx it on the 3rd harmonic. The freqs it uses are 88/90/106/107 in the following increments: .1/.3/.5/.7/.9 giving 20 possible freqs on this model. Does anyone have a newer model that has more freqs available? The newer ones plug into the cigarette lighter and some have a range of around 300'. Thanks for everyone's comments; made for an interesting topic! Now I don't have to ask the question to the "Proof is out there show". lol!

 

[BinaryMode]

Did not know this. Thanks for the update. Am assuming the scanner will not auto switch since that particular band is set with WFM, correct?

If the modulation is set to "auto" in that and other scanners it'll use the modulation that most closely matches that band. For example: 2 Meters ham band will be FM. Tune to the radio broadcast band and the scanner will use WFM. But you can change the modulation per frequency if you want. You're not stuck with just using one type of modulation. My AR-8000 not only has selectable WFM, but SSB, CW, AM and FM.