On Aug 31, 2010, at 1:54 PM, n2gyn wrote:
Most radios are sent to 8bit. Can all radio's bit rate be changed?
I believe it is the LOW bit rate that lowers the quality of d-star's
audio. Is there a sub menu in the radio's. Also can the repeater's
rate be change to a higher rate?
John
John,
I don't understand your question.
Are you talking about the bit rate for the on air signal? For digital
voice, it is fixed at 4800 bps (2400 bps Voice, 1200 bps Voice FEC,
1200 bps DATA) and cannot be changed. For (23cm) digital data, it is
fixed at 128,000 bps. Those are specified in the standard for
interoperability.
Are you talking about the A/D and D/A sample rates for the AMBE
vocoder? (Not adjustable as far as I know)
Are you talking about the data port for GPS/Serial communications?
The GPS setting is 4800 bps (NMEA Standard) and serial communications
depends on radio, but is always 1200 bps for digital voice data on the
air. (128000 bps for digital data in ethernet frames).
Radios and repeaters operate on the same on air bit rate. 4800 bps
for digital voice and 128000 bps for digital data (23cm).
The AMBE vocoder is optimized for intelligibility of the human voice,
amateur radio is a communications service not an entertainment
service, fidelity is sacrificed for a lower data rate. (Quality is
based on intended use. The quality for voice communications is good,
the quality for high fidelity sound reproduction is not so good.)
John D. Hays
Amateur Radio Station K7VE
PO Box 1223
Edmonds, WA 98020-1223 VOIP/SIP: [email protected]
