Technical question on BCD396T

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kg9qm

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When I press and hold the 'Func' button and I tap the 'scroll control', does the radio adjust the audio muting level or the squelch open level?

The user manual doesn't say and the best I can come up with on the internet is this from Uniden and :

http://www.patentgenius.com/patent/5548832.html

It has been contemplated to activate the display light source coincidentally with the activation of the squelch signal output from the receiver. As such, the display light source would illuminate whenever the receiver squelch opened. This isnot a completely satisfactory solution because sometimes the received signal which caused the squelch to open will remain active for an extended period of time, and cause needless current drain from the battery. In such a situation, the user need onlyview the display at the beginning of the signal reception. Further, such a scheme does not deal with the situation where there is sufficient ambient light to view the display, in which case, the display light source need not be illuminated at all.

SUMMARY OF THE INVENTION

In one embodiment, a portable scanning radio receiver is disclosed which includes a liquid crystal display with an incandescent backlight. The display indicates the presently received channel or frequency coincidentally with the activation of asignal present output from the receiver. The signal present output is a conventional squelch signal, but may alternatively be a tone coded squelch or digital squelch signal. In any case, the output has a first state indicating the presence of areceived signal and a second state indicating the cessation of the received signal.

If an auto-light function is enabled, then a controller illuminates the backlight and starts an interval timer. The controller extinguishes the backlight at the occurrence of either the expiration of the interval timer or the cessation of thesignal present output from the receiver.
I would have expected a more accurate description, seeing as how the patent is not just a technical description but also a legal one. But it's the most detailed explanation I have been able to find.
 

UPMan

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Squelch open level. I am not sure what "audio muting level" would be...there is no such setting an any scanner I know of.

The patent is describing the Backlight-on-squelch feature, not a specific radio panel control.
 

kg9qm

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UPMan said:
Squelch open level. I am not sure what "audio muting level" would be...there is no such setting an any scanner I know of.

The patent is describing the Backlight-on-squelch feature, not a specific radio panel control.

Nor one that I had heard of of either, until it was recently explained to me in detail in another thread.
 

torontokris

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Func + scroll changes the squelch level.

I briefly read that thread.. did you mean the
"audio amp enable line circuit" that another member was talking about?
Or something like audio AGC?

Side note I understood what you meant in that thread about keeping the radio ON while a transmission is active.
 

UPMan

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I don't see that anything in that thread allows for a "muting level" adjustment. There is a (nitpicky but accurate) distinction made between squelch and audio. That is, for audio to come out of the speaker multiple conditions have to be met, among which are:

  • Signal level is greater than the squelch threshold
  • Signal contains the correct CTCSS/DCS code (if set for the channel)
  • Signal is a voice transmission and not the control channel (if scanning a trunked system)
  • P25 signal can be decoded (for P25 voice channels)
and I'm sure that there are more that don't immediately come to mind.

The invention summary you cite above mentions only the first two of the above conditions and discusses only conventional (not trunked) operation.
 

pro92b

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kg9qm said:
Nor one that I had heard of of either, until it was recently explained to me in detail in another thread.
It was explained but not understood.

The squelch detector samples noise above 3 kHz and if enough noise is present the squelch gate remains closed. The adjustment you asked about sets the threshold for the squelch gate's noise detector. A sufficiently strong signal will produce enough quieting of the noise to open the squelch gate.

An open squelch gate is not enough to enable the audio output. The squelch gate signal is processed by the CPU along with CTCSS, DCS, and P25 encryption flags to determine if the audio should be passed or not. There is no audio muting threshold although the squelch threshold has a part in determining if the audio is muted.
 

slicerwizard

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kg9qm said:
I would have expected a more accurate description, seeing as how the patent is not just a technical description but also a legal one.
The more accurate or detailed a patent application is, the easier it is for competitors to circumvent it by making minor changes to the design/algorithm/whatever.

So they're often as vague as possible.
 

kg9qm

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torontokris said:
Func + scroll changes the squelch level.

I briefly read that thread.. did you mean the
"audio amp enable line circuit" that another member was talking about?
Or something like audio AGC?

Side note I understood what you meant in that thread about keeping the radio ON while a transmission is active.
It was really not hard to understand. Unless one's a 'Scotty' type who doesn't live outside one's stack of Technical Manuals.
 

torontokris

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Thanks I thought it would be a good feature too.

kg9qm said:
It was really not hard to understand. Unless one's a 'Scotty' type who doesn't live outside one's stack of Technical Manuals.
 
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