Well, the transmitted audio on an NRSC-1 compliant AM transmitter is up to
10 kHz, which gives rise to a channel 20 kHz wide in total bandwidth. An
NRSC-3 (1990) complaint receiver (I think there was only one ever made, the
GE Super Radio) has a recovered audio response of 50 to 7500 Hz, plus
1.5, - 3 dB, referenced at 400 Hz. See:
http://www.nrscstandards.org/Standards/nrsc-3.pdf
Without violating the Nyquist Theorem, a 14 kHz IF should result in at least
6 kHz of recovered AM audio, which the commercial stations are broadcasting
with the exception of some IBOC stations (not all of them), who only in the
daytime hours, reduce their main channel analog audio to 5 kHz, however
their total BW, including the IBOC carriers is around 30 kHz.
Ron Castro
N6AHA
Chief Technical Officer
Results Radio, LLC
----- Original Message -----
From: "Barry LaZar" <k3ndm@verizon.net>
To: "Ron Castro" <ronc@sonic.net>; "Discussion of Ten-Tec Equipment"
<tentec@contesting.com>
Cc: "Ten Tec List" <tentec@contesting.com>
Sent: Thursday, March 16, 2006 11:32 AM
Subject: Re: [TenTec] Orion Sub Receiver BW
> Ron,
> Going to a bandwidth in excess of 10 KHz. really isn't useful. The FCC
> limits the AM BC'ers to a 10 KHz channel and the CCIR limits are less in
> the SW bands.
>
> Barry
> K3NDM
>
>
>>From: Ron Castro <ronc@sonic.net>
>>Date: Thu Mar 16 12:05:06 CST 2006
>>To: Discussion of Ten-Tec Equipment <tentec@contesting.com>
>>Cc: Ten Tec List <tentec@contesting.com>
>>Subject: Re: [TenTec] Orion Sub Receiver BW
>
>>My understanding is that in AM, the BW shown is supposed to be the actual
>>recovered audio bandwidth, not the total bandwidth. There is no reason
>>why
>>it should be restricted to any less than 12 kHz since the DSP IF is 14 kHz
>>wide, and the roofing filter over it is 20 kHz.
>>
>>Ron
>>N6AHA
>>
>>----- Original Message -----
>>From: "joel hallas" <jrhallas@optonline.net>
>>To: "Discussion of Ten-Tec Equipment" <tentec@contesting.com>
>>Sent: Thursday, March 16, 2006 9:59 AM
>>Subject: Re: [TenTec] Orion Sub Receiver BW
>>
>>
>>> Am I missing something here?
>>>
>>> If a DSB AM signal is tuned with the carrier centered in a 6 kHz BW,
>>> I would expect to see just 3 kHz of audio BW. If you tune the carrier to
>>> one edge, you will be able to get a wider audio BW.
>>>
>>> 73, Joel
>>>
>>> Sinisa Hristov wrote:
>>>
>>>>Rick Williams wrote:
>>>>
>>>>
>>>>
>>>>>When I tuned in a local AM station and looked at the audio on HamAlyzer
>>>>>it
>>>>>looked great EXCEPT for one thing. It was only 3000 Hz wide? The
>>>>>audio
>>>>>signal plummeted after 3,000 Hz!
>>>>>
>>>>>
>>>>
>>>>
>>>>I attempted to measure AM RX audio response with 2.056 a few times,
>>>>and in all ocassions it was 3 kHz on both main and sub RX.
>>>>RX filters were fully open and RX was fed from a signal generator
>>>>having adjustable modulation frequnecy.
>>>>
>>>>Audio response was close to 6 kHz with 1.373b5.
>>>>
>>>>
>>>>73,
>>>>
>>>>Sinisa YT1NT, VE3EA
>>>>_______________________________________________
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>>>>
>>>>
>>>>
>>>
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>>>
>>
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