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Re: [Discuss-gnuradio] AR5000 and downconversion
From: |
Joseph DiVerdi |
Subject: |
Re: [Discuss-gnuradio] AR5000 and downconversion |
Date: |
Thu, 15 May 2003 00:04:08 -0600 |
At 11:58 PM -0400 5/14/2003, Krzysztof Kamieniecki wrote:
>John R. Ackermann N8UR wrote:
>> Hi Alan --
>> I doubt you'll find many radios that support a 6-7MHz bandwidth around a
>> 10.7MHz IF. That's way too great a percentage of the center frequency for
>> traditional radio design to work with. I suspect the 10.7 IF in the AR5000
>> is not going to be able to handle more than NBFM, or at most WBFM (eg,
>> 200kHz or so) bandwidth without major surgery that would likely render the
>> radio useless for normal tasks. A radio that supports TV bandwidths is
>> likely to have a much higher IF, anywhere from 45 to 70MHz or higher.
>> John
><snip>
>
>The ar5000 has a bandwidth of 10mhz
>http://www.aorja.com/ar5000e.html
>http://www.aoruk.com/5000bull.htm
>
>AOR claims there is a NTSC demodulator for the ar5000 it's called TV5000
>
>Rumors says ar8600 has either 2 or 4 mhz bandwidth (i've seen both mentioned)
>Krzysztof Kamieniecki
Couldn't help adding my two cents here.
I must agree with John's original comments - based on "conventional RF design
wisdom" the bandwidth of a 10.7MHz IF is generally much less than +/- a few
hundreds of kHz. Unless something unusual is going on there will likely be real
problems with adjacent channel interference.
A snippet of the ar5000e.html URL cited above by Krzysztof follows:
"The receive circuitry is a triple conversion superheterodyne with IFs of
622MHz, 10.7MHz & 455kHz. Multiple switchable IF bandwidth are available in
both the 10.7MHz and 455kHz IF stages: 3kHz, 6kHz, 15kHz, 30kHz, 110kHz, &
220kHz with provision for an optional 500Hz Collins mechanical filter."
These values make sense for a communications receiver. There are three
sequential IFs (good design technique but can be a bit pricey) and the
bandwidth specified for the second and third IFs is quoted in the tens and
hundreds of kHz. Again, it is unlikely that the hundreds of kHz bandwidth
values are available at the third IF (455kHz) but more likely available from
the a tap of the second IF (10.7MHz).
As Krzysztof also notes there is a quote on the page referenced by the same URL
which follows:
"The AR5000 is ready to plug straight into the optional SDU5500 spectrum
display unit for "real time" band occupancy evaluation and measurements in both
frequency and dBm signal level. The 10.7MHz I.F. output of the AR5000 has a
suitable 10MHz bandwidth ideally matched to the SDU5500."
Now this is really curious. I would not be surprised to see a 10MHz bandwidth
available from the *first* IF (622MHz) but am dubious of the claim as written.
It *is* possible but would be highly unusual.
Need to look into this a bit more but getting sleepy, sleepy, sleepy...
Best regards,
Joseph
--
Joseph A. DiVerdi, Ph.D., M.B.A.
http://xtrsystems.com/ 970.980.5868 (voice)
PGP Key ID: 0xD50A9E33
- [Discuss-gnuradio] AR5000 and downconversion, Alan Gray, 2003/05/14
- Re: [Discuss-gnuradio] AR5000 and downconversion, brian whitaker, 2003/05/14
- Re: [Discuss-gnuradio] AR5000 and downconversion, Alan Gray, 2003/05/14
- Re: [Discuss-gnuradio] AR5000 and downconversion, John R. Ackermann N8UR, 2003/05/14
- Re: [Discuss-gnuradio] AR5000 and downconversion, Dave Emery, 2003/05/14
- Re: [Discuss-gnuradio] AR5000 and downconversion, Krzysztof Kamieniecki, 2003/05/14
- Re: [Discuss-gnuradio] AR5000 and downconversion,
Joseph DiVerdi <=
- Re: [Discuss-gnuradio] AR5000 and downconversion, Joshua Lackey, 2003/05/15
- Re: [Discuss-gnuradio] AR5000 and downconversion, Krzysztof Kamieniecki, 2003/05/15
- Re: [Discuss-gnuradio] AR5000 and downconversion, Joshua Lackey, 2003/05/15
- Re: [Discuss-gnuradio] AR5000 and downconversion, Krzysztof Kamieniecki, 2003/05/15
- Re: [Discuss-gnuradio] AR5000 and downconversion, John Gilmore, 2003/05/15
Re: [Discuss-gnuradio] AR5000 and downconversion, Henrique Miranda, 2003/05/14
Re: [Discuss-gnuradio] AR5000 and downconversion, Robert Kelley, 2003/05/14