Com Dev Wireless Group GLOBALCELL-IID Manuale Utente
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From: brett@comdev.cc
To: norwoodpatterson@msn.com
Subject: answers for manuals
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Date: 8 Jan 2000 01:24:43 -0000
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From: brett@comdev.cc
To: norwoodpatterson@msn.com
Subject: answers for manuals
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Norwood,
Here are the answers to the 4 questions that you requested. If you need
anything more please give me a call.
anything more please give me a call.
-Brett
Brett Moser, Senior System Architect brett.moser@comdev.cc
Phone: (805) 544-1089 Fax: (805) 544-2055 http://www.comdev.cc/
COM DEV Wireless Group - Digital and Software Systems
863 Pacific Street, San Luis Obispo, CA 93401
Phone: (805) 544-1089 Fax: (805) 544-2055 http://www.comdev.cc/
COM DEV Wireless Group - Digital and Software Systems
863 Pacific Street, San Luis Obispo, CA 93401
1) Description of the oscillator circuit and how the temperature effect is
stabilized
stabilized
The oscillator circuit is referenced to an oven controlled crystal oscillator.
The oven controlled crystal oscillator has a 0.5ppm frequency stability over
the temperature range of -30 degrees C to 60 degrees C.
The oven controlled crystal oscillator has a 0.5ppm frequency stability over
the temperature range of -30 degrees C to 60 degrees C.
2) Description of the audio limiting circuit
The audio limiting circuit is implemented in a Digital Signal Processor.
The signal input into the audio limiting circuit has a range of [-1,1). The
refrence level used through the system is a 1kHz tone with an amplitude of
+/- 2^(-6.5) produces a FM modulated carrier with 2.9kHz peak frequency
deviation. The audio limiting circuit thus limits the peak signal amplitude
to +/- 0.04578.
The signal input into the audio limiting circuit has a range of [-1,1). The
refrence level used through the system is a 1kHz tone with an amplitude of
+/- 2^(-6.5) produces a FM modulated carrier with 2.9kHz peak frequency
deviation. The audio limiting circuit thus limits the peak signal amplitude
to +/- 0.04578.
3) Description of the audio low pass filter
The audio low pass filter is implemented in a Digital Signal Processor. The
filter is a 25 tap interpolate-by-5 FIR filter with a cut-off frequency of
3kHz.
filter is a 25 tap interpolate-by-5 FIR filter with a cut-off frequency of
3kHz.
4) Desciption of the RF spurious filter
The RF spurious filtering is performed by two components: the high power
cavity tune combiners, and the transmit bandpass filter. The high power
cavity tune combiners provide 20-30dB attenuation 300kHz outside the channel.
The transmit bandpass filter attenuates spurious emmisions outside the transmit
cellular band of 870MHz - 894MHz.
cavity tune combiners, and the transmit bandpass filter. The high power
cavity tune combiners provide 20-30dB attenuation 300kHz outside the channel.
The transmit bandpass filter attenuates spurious emmisions outside the transmit
cellular band of 870MHz - 894MHz.