Additions:
Deletions:
Additions:
Or How I Calibrated my Icom 756 Pro III to 1 hz frequency accuracy using only a laptop and free software :)
The radio I used for this was an Icom 756 Pro III and the computer was running XP. First I located a program that will display the output of the receiver to the soundcard in a waterfall display. Most digital mode programs will do this. I chose the free Spectrum Lab software which is particularly suited to this purpose (see link below). Digipan is another popular choice.
Warm up the receiver for a few hours. Install the software on the PC and cable the audio to the sound card. Tune to 10.000 Mhz and set the mode to AM. The modulation and tones from WWV must be strong enough to see on the waterfall display. WWV uses different tones through the minutes, so wait for and observe the 500 hz tone on the waterfall display. It should be right on 500 hz waterfall mark, but even if not note where it is, and use that spot for the tuning later on.
Change the mode of the receiver to USB and set the tuning to 9.9995 mhz. The carrier of WWV's signal should be visible at the 500 hz point, or near there. The amount away from 500 hz is the error of the receiver. Adjust the receiver's calibration adjustment to bring the tone to exactly 500 hz to calibrate the receiver.
Deletions:
Or How I Calibrated my Icom 756 Pro III to 1 hz frequency accuracy with only a laptop and free software :)
The radio I used for this was an Icom 756 Pro III and the computer was running XP. First I located a program that will display the output of the receiver to the soundcard in a waterfall display. Most digital mode programs will do this. I chose the free Spectrum Lab software which is particularly suited to this purpose (see link below).
Warm up the receiver for a few hours. Install the software on the PC and cable the audio to the sound card. Tune to 9.9995 Mhz and set the mode to AM. The modulation and tones from WWV must be strong enough to see on the waterfall display. WWV uses different tones through the minutes, so wait for and observe the 500 hz tone on the waterfall display. It should be right on 500 hz waterfall mark, but even if not note where it is, and use that spot for the tuning later on.
Change the mode of the receiver to USB, with the tuning still set at 9.9995 mhz. The carrier of WWV's signal should be visible at the 500 hz point, or near there. The amount away from 500 hz is the error of the receiver. Adjust the receiver's calibration adjustment to bring the tone to exactly 500 hz to calibrate the receiver.
Additions:
Here is a simple procedure that will allow you to check and calibrate the frequency of your HF Receiver or Transceiver. It is accurate to 1hz or better, and requires very little equipment. It does not require an oscilloscope or accurate frequency counter or "zero beating" a signal that is difficult to do and generally does not work well. You can easily see the error and watch it over time as the receiver warms up.
Receiver or Transceiver with antenna sufficient to pick up WWV (or other frequency standard transmissions)
Software to display sound card audio input as a frequency waterfall
Deletions:
Here is a simple procedure that will allow you to check and calibrate the frequency of your HF Receiver or Transceiver. It is accurate to 1hz or better, and requires very little equipment.
Receiver or Transceiver with antenna sufficient to pick up WWV or other frequency standard transmissions
Software to display audio input as a frequency waterfall
Additions:
The radio I used for this was an Icom 756 Pro III and the computer was running XP. First I located a program that will display the output of the receiver to the soundcard in a waterfall display. Most digital mode programs will do this. I chose the free Spectrum Lab software which is particularly suited to this purpose (see link below).
Warm up the receiver for a few hours. Install the software on the PC and cable the audio to the sound card. Tune to 9.9995 Mhz and set the mode to AM. The modulation and tones from WWV must be strong enough to see on the waterfall display. WWV uses different tones through the minutes, so wait for and observe the 500 hz tone on the waterfall display. It should be right on 500 hz waterfall mark, but even if not note where it is, and use that spot for the tuning later on.
Deletions:
The radio I used for this was an Icom 756 Pro III and the computer was running XP. First I located a program that will display the output of the receiver in a waterfall display. Most digital mode programs will do this. I chose the free Spectrum Lab software (see link below).
Warm up the receiver for a few hours. Install the software on the PC and cable the audio to the sound card. Tune to 9.9995 Mhz and set the mode to AM. The modulation and tones from WWV must be audible. WWV uses different tones through the minutes, so observe the 500 hz tone on the waterfall display. It should be right on 500 hz, but even if not note where it is, and use that spot for the tuning later on.
Additions:
Or How I Calibrated my Icom 756 Pro III to 1 hz frequency accuracy with only a laptop and free software :)
Additions:
The ARRL FMT (Frequency Measurement Test) will be a further test of this technique of calibrating WWV and measuring frequency using audio FFT. See the FMT page below for more information.
Deletions:
The upcoming ARRL FMT (Frequency Measurement Test) will be a further test of this technique of calibrating WWV and measuring frequency using audio FFT. See the FMT page below for more information.
Additions:
Software to display audio input as a frequency waterfall
The radio I used for this was an Icom 756 Pro III and the computer was running XP. First I located a program that will display the output of the receiver in a waterfall display. Most digital mode programs will do this. I chose the free Spectrum Lab software (see link below).
Deletions:
The radio I used for this was an Icom 756 Pro III and the computer was running XP. First I located a program that will display the output of the receiver in a waterfall display. Most digital mode programs will do this. I chose Spectrum Lab (see link below).
Additions:
Equipment Required
Receiver or Transceiver with antenna sufficient to pick up WWV or other frequency standard transmissions
Computer with sound card
Cable to connect audio from receiver to sound card (optionally a Y cable to run sound to headphones at the same time)
Deletions:
Equipment Required
Receiver or Transceiver with antenna sufficient to pick up WWV or other frequency standard transmissions
Computer with sound card
Cable to connect audio from receiver to sound card (optionally a Y cable to run sound to headphones at the same time)
Receiver Frequency Calibration
Here is a simple procedure that will allow you to check and calibrate the frequency of your HF Receiver or Transceiver. It is accurate to 1hz or better, and requires very little equipment.
Equipment Required
Receiver or Transceiver with antenna sufficient to pick up WWV or other frequency standard transmissions
Computer with sound card
Cable to connect audio from receiver to sound card (optionally a Y cable to run sound to headphones at the same time)
The radio I used for this was an Icom 756 Pro III and the computer was running XP. First I located a program that will display the output of the receiver in a waterfall display. Most digital mode programs will do this. I chose Spectrum Lab (see link below).
Warm up the receiver for a few hours. Install the software on the PC and cable the audio to the sound card. Tune to 9.9995 Mhz and set the mode to AM. The modulation and tones from WWV must be audible. WWV uses different tones through the minutes, so observe the 500 hz tone on the waterfall display. It should be right on 500 hz, but even if not note where it is, and use that spot for the tuning later on.
Change the mode of the receiver to USB, with the tuning still set at 9.9995 mhz. The carrier of WWV's signal should be visible at the 500 hz point, or near there. The amount away from 500 hz is the error of the receiver. Adjust the receiver's calibration adjustment to bring the tone to exactly 500 hz to calibrate the receiver.
My experience with my Icom 756 Pro III was that it started a couple of hz high and drifted to about 10 hz high. I adjusted it to within a half hz or so of the 500 hz reference. My soundcard calibration was right on, I could not see any error in that at least to 0.1 hz or so. I also read the frequency of the built in calibrator for the Pro and on my unit it is almost 2hz low. Not bad for a rig that is several years old and been to the field numerous times. I'm not sure yet how to adjust the calibration oscillator, but the receiver is doing quite well. I will make further checks in the coming days to see if it stays on.
The upcoming ARRL FMT (Frequency Measurement Test) will be a further test of this technique of calibrating WWV and measuring frequency using audio FFT. See the FMT page below for more information.
73,
References
Spectrum Lab Software∞
FMT = Frequency Measurement Test
AlanB