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- Missatge Original -
De: Andrew O'Brien [EMAIL PROTECTED]
Data: Dimarts, Octubre 7, 2008 2:21 am
Assumpte: Re: [digitalradio] EA3AQS CQing MT63
Destinatari: digitalradio@yahoogroups.com
Andrew, I use Mixw 2.18 program for data modes . About MT63 never
have got troubles in TX/RX. Time
It means that the drivers are better - the internal clock runs at 48kHz,
other rates are created by either the driver or (very often) Windows.
Windows XP does not do a good job of this, VISTA however is excellent at
converting the sample rates.
Simon Brown, HB9DRV
www.ham-radio-deluxe.com
Thanks, Simon! It makes sense that if the native speed is 48K, any
other speed would require some type of conversion.
One more question, if I can impose on your good nature!
What impact, if any, does the error in sampling rate have on any
TX/RX offset? During the Tara Rumble I noticed that
A significant difference between TX and RX can result in an offset. During
my holidays in Oct / Nov I will add full soundcard calibration for all modes
in DM780.
Simon Brown, HB9DRV
www.ham-radio-deluxe.com
- Original Message -
From: Dave [EMAIL PROTECTED]
What impact, if any, does
Here's a goody for someone knowledgeable about sound cards.
I've calibrated my sound card (Diamond PCI) two ways, using MMSSTV
at 48000 Hz, and MMTTY at 11025 Hz. Here are the results of the
calibration:
MMSSTV 195 PPM 48009.37
MMTTY 6984 PPM 11102
This seems to be a huge
Hello Dave,
It is simple. If the offset in sampling frequency is x% and the true AF
frequency is f0, the displayed frequency f will be equal to
f=f0*(1-x/100)
Example: if the sampling offset is +1% and f0 is 1000 Hz, the frequency
displayed will be equal to 1000*(1-0.01)=990 Hz
73
Patrick
Thanks, Patrick!
If I understand this, then, here is what I should expect:
My sound card calibrates to 48009.37, which is .9998% fast
I transmit with an audio frequency of 2415 Hz
I am therefore actually transmitting on 2439 Hz, or .9998% higher
than indicated
Does that
Dave,
My sound card calibrates to 48009.37, which is .9998% fast
So the offset is +0.0195 %
I transmit with an audio frequency of 2415 Hz
I am therefore actually transmitting on 2439 Hz, or .9998% higher
No in TX it will be the reverse of RX. The true TX frequency will be equal
to :
