BC125AT: BC125AT Birdies?

[ErikSwan]

I recently purchased a BC125AT as my first scanner, mostly to use for airband and general analog scanning before possibly exploring a more expensive and capable scanner like the SDS100, but I'm a little dissappointed with the number of birdies that I'm picking up with the BC125AT.

To get away from the local RF noise in my electronics-filled home, I took it to a local park and just started a basic "custom search" just to see what I could find prior to programming the scanner. I noticed that the scanner would lock and break squelch on quite a number of frequencies that didn't seem to have anything on them - I would just hear white noise, complete silence, or occasionally, more of an impulse-type static sounding noise.

When I got home, I ran a basic test: I reset the scanner to factory defaults, removed the antenna, and started a "quick search" at 25 MHz and let it search through the entire frequency range supported by the scanner.

I was surprised to find that at the default squelch setting (2) it was still stopping and breaking a squelch on a large number of frequencies and picking up what must be spurious signals/birdies from inside the scanner.

Here is the complete list of frequencies I had to lockout before it would complete a full search through the entire frequency range without stopping on a spurious signal:

28.5500
30.8000
30.9900
32.0000
34.0500
38.9750
39.3300
47.6700
49.4000
125.1000
135.0500
144.3500
145.9500
155.9025
165.2000
229.3500
239.3000
250.2000
256.5375
260.1500
271.0500
277.3875
281.0000
282.6000
287.8125
291.9000
293.0250
298.2375
303.4500
308.6625
312.7500
313.8750
319.0875
323.7500
350.9000
354.4500
361.3250
363.7875
365.4500
369.0000
371.7500
374.2125
375.3000
379.4250
400.2750
405.4875
406.5750
407.1500
410.7000
411.7875
415.9125
417.0000
421.1250
426.3375
428.0000
431.5500
436.7625
437.8500
441.9750
448.8500
452.4000
458.7000
462.2250
462.8250
469.7000
473.2500
476.3125
479.5500
483.6750
490.5500
500.4000
511.4000

Again, to re-iterate, this is with the antenna completely removed, so these are not "real" signals.

Is this normal? At the default squelch level (2), that's 72 of the 100 available permanent lockout slots used just to lockout the internal birdies of the receiver!

The scanner does appear to otherwise work normally - I've been able to pick up airband signals quite well and occasionally close call will get triggered by what appears to be a very high-powered POCSAG pager transmitter nearby.

Are my expectations too high for a $100 consumer scanner, or is something wrong with my individual unit?

 

[steve9570]

I bought one last month I have many scanners and Minitor pagers I use and no problems with the 125AT. You may have a issue with that unit. Mine works fine.

 

[wtp]

i was trying to find an official list and the definition of birdie was on page 72...
but no list

https://www.uniden.info/download/ompdf/BC125ATom.pdf

even the expensive radios will have them.

 

[ErikSwan]

I bought one last month I have many scanners and Minitor pagers I use and no problems with the 125AT. You may have a issue with that unit. Mine works fine.

I was initially leaning towards something being wrong with it (especially since I purchased it as open box from Amazon Warehouse), but it appears to perform just fine with real signals, specifically airband. I say "appears to perform fine" because I don't really have anything to compare it to, but it's definitely not completely broken.

If you set the squelch to 2, take the antenna off, and do a Quick Search or Custom Search through the whole frequency range, does yours stop on any internal birdies?

 

[RidingDownUnder]

Try removing the antenna and see if you still receive birdies?

 

[ErikSwan]

Try removing the antenna and see if you still receive birdies?

All of the testing I did was with the antenna removed.

 

[RidingDownUnder]

I think there’s a problem with the 125 to have that many frequencies with noise with no antenna. If you purchased it new take it back for a exchange because that model has very good feedback from users of airband and railroad fans. It’s unfortunate.

 

[KevinC]

I don't own the 125, but 72 birdies out of thousands of frequencies isn't all that bad.

 

[wtp]

so with no birdies in the air or rail bands, he should roll the dice and take his chances.
i remember some big name radio that skipped some band area due to having birdies there.

 

[ErikSwan]

I don't own the 125, but 72 birdies out of thousands of frequencies isn't all that bad.

You're right, it's really not that bad.

I'm mostly just trying to get an understanding if I have a bad unit that I should try to return or if this is considered normal. Hoping maybe someone else with a 125AT could try to replicate my results.

 

[lamarrsy]

Maybe something generating very wideband noises in your vicinity ?
Have you tried the same tests, but outside and relatively far from the home ?

…just an intuition that it could be related to a powerful noise-generating source nearby.

‘Let us know !

 

[Scan125]

I did a test on my UBC125XLT USB coupled and controlled via my PC and found as follows: (no antenna)

Squelch Setting (2 to 15) (Y=Stops, P=Briefly Pauses, N=No Stop)

2 3 5 10 15
- - - -- --
032.0000 Y Y Y Y
041.7000 Y N N N
048.0000 Y Y Y N
062.5500 Y Y Y Y
125.1000 Y Y N N
384.0000 Y Y Y Y (beating @ 0.5 second interval so probably a real signal)
865.7500 Y Y N N
886.5000 Y Y Y N

 

[Scan125]

I did a test on my UBC125XLT USB coupled and controlled via my PC and found as follows: (no antenna)

Squelch Setting (2 to 15) (Y=Stops, P=Briefly Pauses, N=No Stop)

2 3 5 10 15
- - - -- --
032.0000 Y Y Y Y
041.7000 Y N N N
048.0000 Y Y Y N
062.5500 Y Y Y Y
125.1000 Y Y N N
384.0000 Y Y Y Y (beating @ 0.5 second interval so probably a real signal)
865.7500 Y Y N N
886.5000 Y Y Y N

Same test on UBC75XLT

2 3 5 10 15
- - - -- --
041.4750 Y Y Y N
041.7000 Y Y Y N
055.2950 Y Y Y N
069.1200 Y Y Y Y

Note UBC75XLT is only 25.0 to 88.0, 108 to 174, 400 to 512 MHz

 

[Ubbe]

What's the step size for BC versus UBC?

My sat box, computer and display screens interferes directly into some scanners without antenna connected and sometimes there's a continuous data stream heard that has a pattern that could be heard changing if I switch sat channel or another resolution are used in a screen. But often its just a plain carrier in the 200MHz-400MHz range that disappears when the device that creates it are powered off or if I move a portable scanner to another room.

I have a Chinese security camera that generates a carrier with a flow modulated whirling noise in the 170MHz band that can be heard in the whole house. I initially though it came from outside and went outdoors and moved towards the signal until I stood outside my window with that camera behind the glass. I disconnected its power and the carrier disappeared.

/Ubbe

 

[Scan125]

BC125AC: 5kHz, 6.25kHz, 8.33kHz, 12.5kHz

UBC125XLT: 5kHz, 6.25kHz, 8.33kHz, 10.0 kHz, 12.5kHz, 20kHz

 

[ecps92]

i was trying to find an official list and the definition of birdie was on page 72...
but no list

https://www.uniden.info/download/ompdf/BC125ATom.pdf

even the expensive radios will have them.

I miss the days, when the paper manual listed all the birdies tweet tweet

 

[Ubbe]

I read both user manuals for UBC and BC125 and it only differs for the bandplan of high VHF, so they should detect the same birdies if the hardware are the same and no components have been substituted due to them being obsolete.

/Ubbe

 

[ErikSwan]

I re-ran the experiment with the squelch set to the maximum of 15, and found that it's still picking up the following birdies (again, still with the antenna removed):

28.5500
30.8000
30.9900
32.0000
34.0500
39.3300
49.4000
125.1000
135.0500
145.9500
155.9025
239.3000
271.0500
281.0000
291.9000
312.7500
313.8750
323.7500
354.4500
369.0000
374.2125
379.4250
400.2750
405.4875
410.7000
415.9125
417.0000
421.1250
428.0000
431.5500
437.8500
441.9750
448.8500
452.4000
462.2250
462.8250
469.7000
479.5500
500.4000
511.4000

It's definitely a smaller number than before (40 vs. 72), but this almost seems like an even worse result to me since it's with the squelch set to the maximum possible value!

It still seems like a very large number of birdies, especially compared to @Scan125's results above, although the BC125AT is technically a different model than the UBC125XLT.

I've decided to order a brand-new BC125AT to compare (no Amazon Warehouse this time) and will run the same test and return whichever unit performs worse.

Maybe something generating very wideband noises in your vicinity ?
Have you tried the same tests, but outside and relatively far from the home ?

…just an intuition that it could be related to a powerful noise-generating source nearby.

‘Let us know !

My sat box, computer and display screens interferes directly into some scanners without antenna connected and sometimes there's a continuous data stream heard that has a pattern that could be heard changing if I switch sat channel or another resolution are used in a screen. But often its just a plain carrier in the 200MHz-400MHz range that disappears when the device that creates it are powered off or if I move a portable scanner to another room.

I have a Chinese security camera that generates a carrier with a flow modulated whirling noise in the 170MHz band that can be heard in the whole house. I initially though it came from outside and went outdoors and moved towards the signal until I stood outside my window with that camera behind the glass. I disconnected its power and the carrier disappeared.

/Ubbe

I guess it is possible I have some extremely strong local wide-band noise source or a collection of strong noise sources, but it seems unlikely it would be so bad as to bring out all these extra birdies even with the squelch on the 125AT set to maximum. However, I'm going backpacking way out in the wilderness this weekend so I will try to bring it along and run the same test in what should be the cleanest RF environment I can possibly find.

 

[wtp]

the call signal is coming from inside the house radio.

 

[Scan125]

I read both user manuals for UBC and BC125 and it only differs for the bandplan of high VHF, so they should detect the same birdies if the hardware are the same and no components have been substituted due to them being obsolete.

/Ubbe

I seem to recall that Unidan Man Paul Optiz (very sadly RIP and missed) said that the BC125AT and UBC125XLT were internally different. I have the schematics for the UBC125XLT so if someone has the same for the BC125AT then they can do a compare. The UBC125XLT does have a larger frequency range compared to the BC125AT so if nothing else filters and internal oscillator "stuff" must have changed.

See: Scan125 Control Program User Manual