AR-DV1 FM Fidelity / "Auto" Vs. "FM" Mode

[MStep]

Here is a quick question--- perhaps someone else who has made this observation may be able to explain. Why does the fidelity of an FM signal sound so much better when the DV1 is in "Auto" mode, as opposed to when it is in FM mode? I've tried experimented with IF-BW, but that does not help. Thanks.

 

[MStep]

Quite a few "looks" but no replies. So perhaps first I should ask, does anyone else experience this anomaly? Or is it an anomaly--- perhaps it is within the set's design specifications? I realize that there are very few DV1s in circulation, especially here in the United States, but someone must have experimented with the unit.

 

[wtp]

i don't have that radio.
but as a shot in the dark, auto usually means default.
you are probably listening to a narrow FM transmission on FM regular.
(i will not use wide FM as it gets confusing)
and yes, listening to a narrow one will do this. and might even sound lower in volume.
from a manual

FM – There are two common types of FM (Frequency Modulation):

NFM – Narrow Band Frequency Modulation
Provides high quality communication for relatively short distance operations.
FM uses a greater frequency bandwidth than other modes.

NFM is the most common mode used above 30 MHz with the exception of the airbands. NFM is
widely used on the VHF bands: VHF marine band, 2m amateur band, 70 cm amateur band, PMR
(Private Mobile Radio) and utilities
and that is from

AOR USA ARDV1 Communications Receiver User Manual AOR AR 110 Steel picture facsimile unit

User manual instruction guide for Communications Receiver ARDV1 AOR USA Inc..

usermanual.wiki

 

[MStep]

i don't have that radio.
but as a shot in the dark, auto usually means default.
you are probably listening to a narrow FM transmission on FM regular.
(i will not use wide FM as it gets confusing)
and yes, listening to a narrow one will do this. and might even sound lower in volume.
from a manual

FM – There are two common types of FM (Frequency Modulation):

NFM – Narrow Band Frequency Modulation
Provides high quality communication for relatively short distance operations.
FM uses a greater frequency bandwidth than other modes.

NFM is the most common mode used above 30 MHz with the exception of the airbands. NFM is
widely used on the VHF bands: VHF marine band, 2m amateur band, 70 cm amateur band, PMR
(Private Mobile Radio) and utilities
and that is from

AOR USA ARDV1 Communications Receiver User Manual AOR AR 110 Steel picture facsimile unit

User manual instruction guide for Communications Receiver ARDV1 AOR USA Inc..

usermanual.wiki

Thanks for your reply. This is something very specific to the DV1 series. There appears no way to create the same audio quality fidelity in "FM" as when is in "Auto" mode. That's why it's important that someone who actually has the radio check in with their findings. Thanks again.

 

[dlwtrunked]

I would check what IF bandwidth you are set at in manual mode if you have not done that.

 

[MStep]

I would check what IF bandwidth you are set at in manual mode if you have not done that.

Been through all the available bandwidths for the FM mode. Still cannot replicate the fidelity of "Auto" mode. Do you also have the DV1?

 

[Ubbe]

Also check Noise Reduction and Notch settings, if they are stored individually to the manual and auto settings.

/Ubbe

 

[G8PTN]

Hi All,

I rarely use the DV1 in Auto mode, but I have repeated your test and can confirm that there is indeed a difference in audio quality between FM auto mode and non-auto mode.

In Auto mode, the FM IF bandwidth is automatically set to 15kHz.

In Non-Auto mode selecting FM, IF Bandwidth 15kHz, NR Off does not produce the same audio quality.

Regards, Dave

 

[G8PTN]

I suspect the audio processing path which is all done by DSP is different in Auto and Non-Auto mode for whatever reason.

In practice the SNR performance is slightly better in Non-Auto mode with the IF bandwidth set to 6kHz (NFM).

Regard, Dave

 

[MStep]

Hi All,

I rarely use the DV1 in Auto mode, but I have repeated your test and can confirm that there is indeed a difference in audio quality between FM auto mode and non-auto mode.

In Auto mode, the FM IF bandwidth is automatically set to 15kHz.

In Non-Auto mode selecting FM, IF Bandwidth 15kHz, NR Off does not produce the same audio quality.

Regards, Dave

This is what I suspected. But AOR is being very cagey about the difference, only to tell my friend several months ago that the "DA" (Digital Audio) circuits that are employed to allow the radio to recognize different digital modes are of "proprietary" design and could not be discussed further.

 

[citiot]

I can also confirm same behavior in mine.

 

[MStep]

I can also confirm same behavior in mine.

Thanks for confirming. As G8PTN stated: " I suspect the audio processing path which is all done by DSP is different in Auto and Non-Auto mode for whatever reason." And I suspect that reason is to accommodate the automatic recognition of most of the digital transmission modes. I don't believe that Tetra is included in the Automatic mode. It would appear that the algorithm they are using in Digital Auto mode has the beneficial side effect of adding some increased fidelity to FM signals only available when the radio is in "Auto" mode, and not "FM" mode, regardless of FM IFBW chosen. AOR remains silent about this phenomenon, lest for the word "Proprietary".

Thank you all.