On 2 Jun 2005 at 16:12, Robert Foxworth wrote:
> Speaking of the NRSC mask, I have just been given a piece
> of equipment that is considered to be obsolete, given the
> direction the industry AM is seen as headed. Maybe someone
> on the list has heard of it. It is reportedly built to measure
> compliance with the NRSC mask for analog AM radio, and
> had a sizable price tag.
>
> It is an AM Splatter Monitor, made by Delta Electronics of
> Alexandria VA. The test sticker is dated in 1994 and the unit
> serial number is in 2 digits, i.e. well below 100.
>
> Anyone ever see or use one of these? The active antenna has been
> lost, but there may be an instruction manual they can find for it.
>
> Looks as if it probably doesn't have a lot of gain for "DXing".
>
It was intended for use according to Sec. 73.44 as a less expensive
way of satisfying the intent of keeping audio within 10.2 kHz of
carrier. The rule permits its use but says a spectrum analyzer
will be the final evidence in disputed cases.
This was something the NRSC thought up when Tek scopes with 7L5
spectrum analyzer plug-ins were very dear. IIRC Delta still
carries it in their product line.
Gain will be very limited because the rule requires measurements
at approximately 1 km from the antenna. You might try it with
a wideband preamp fed by a couple of notch filters for the
worst locals.
With the new standards for IBOC, it is obsolete. Now, to measure
a spectrum you need a spec./an. with at least 100 dB dynamic range,
300 Hz resolution bandwidth and both peak and averaging modes.
Phil Alexander, CSRE, AMD
Indianapolis
--
No virus found in this outgoing message.
Checked by AVG Anti-Virus.
Version: 7.0.322 / Virus Database: 267.5.1 - Release Date: 6/2/05