BitX40 v1.27.7 SPOT mode
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I am using Allard's wonderful v1.27.7 sketch in my BitX40, and because of an trip planned this weekend was rushing to package it so it could be used. I have added the PTT sense line, a FCN switch, and a SPOT switch, and have significantly shortened leads in this final package. Everything seems to be working well and I was able to use the rig mobile. When I press SPOT I am able to fine tune in LSB mode very easily, but the frequency displayed in SPOT mode differs from what the normal display shows. For example, if I am on 7.255.00 and press SPOT, the display reads 7.254.955, so if I tune that to 7.255.00 and release SPOT I get 7.255.05 on the normal display. Am I doing something wrong? Is there some sort of offset in LSB SPOT that needs to be adjusted? ? 73, =Vic= WA4THR |
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Vic,
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There's nothing wrong, it's just a matter of rounding. In SPOT/Fine tune mode, the display shows the actual frequency at 1 Hz precision. In normal mode the precision is 100 Hz, so we need to round the number to the nearest 100 Hz. So if the real frequency (as shown in fine tune mode) is for example 7.254.955 Hz, it will be rounded to 7.255.0 on the display in normal mode. Rounding is performed as follows: f(display) = int ( f(actual) + 50 ) 73 Allard PE1NWL On Sat, February 3, 2018 12:33, Vic WA4THR via Groups.Io wrote:
I am using Allard's wonderful v1.27.7 sketch in my BitX40, and because of |
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Ah, that explains!
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In your case you'd need to round to the nearest 10 Hz. at line 481: ultoa((frequency + 50), b, DEC); // construct the frequency string change to: ultoa((frequency + 5), b, DEC); // construct the frequency string 73 Allard PE1NWL On Sat, February 3, 2018 20:34, Vic WA4THR via Groups.Io wrote:
Thanks, Allard. I'm thinking perhaps to eliminate the +50 in my version |
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The CAL VALUE x 100 represents the offset (in Hz) that we need to apply to
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the nominal VCOA frequency (875 MHz) in order to get the correct output frequency. So the ppm (parts per million) value can be calculated as follows: ppm = CAL VALUE x 100 / 875,000,000 x 1,000,000 For example, the default CAL value is 1575 so the corresponding default ppm value is 1575 x 100 / 875,000,000 x 1000,000 = 180 ppm Hope this helps. 73 Allard PE1NWL On Sun, February 4, 2018 18:51, Vic WA4THR via Groups.Io wrote:
OK, great! One other question...what is the relationship between the "PPM" |
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Yes it does, I never would have figured that out! I wanted to include that appropriate CAL value in my version of your sketch to pretty much get it calibrated correctly when restored to those settings.
Allard, I continue to be impressed and amazed at your software. Thanks so much for this service you have provided. 73, =Vic= WA4THR |
Vic WA4THR
Allard PE1NWL