Day: April 17, 2018

With a signal generator, you can measure the characteristics of your IF filters.

The output of the signal generator, 7015kHz CW, is loosely coupled to IC-7410, and the signal strength is observed while tuning the receiver from 7014kHz to 7016.5kHz with the step size of 100Hz.

import sys
import numpy as numpy
import matplotlib.pyplot as plt
import serial

ser = serial.Serial('/dev/ttyUSB0', 19200, timeout=1)

xvalue = []
yvalue = []

for freq_10hz in range(701400, 701650, 1):
	hz10   = freq_10hz           % 10
	hz100  = freq_10hz //     10 % 10
	khz    = freq_10hz //    100 % 10
	khz10  = freq_10hz //   1000 % 10
	khz100 = freq_10hz //  10000 % 10
	mhz    = freq_10hz // 100000 % 10

	set_freq = b'\xfe\xfe\x80\xe0\x05'     \
			+bytes([16*hz10        ])      \
			+bytes([16*khz   +hz100])      \
			+bytes([16*khz100+khz10])      \
			+bytes([          mhz  ])      \
			+b'\x00\xfd'
	ser.write(set_freq)
	data1 = ser.read(18) # not 17 to raise timeout
	
	get_Smeter = b'\xfe\xfe\x80\xe0\x15\x02\xfd'
	ser.write(get_Smeter)
	data2 = ser.read(16)
	signal = int( data2.hex()[26:30] )
	freq = freq_10hz/100.0
	xvalue.append(freq)
	yvalue.append(signal)
	print(freq, signal)

ser.close()

plt.figure(1, figsize=(8,8))
plt.subplot(111)
plt.grid(True)
plt.plot(xvalue, yvalue, color='red', linewidth=3)
plt.show()

The receiver has three difital IF filters, each with presettable bandwidth. The graph shows my current settings.

Let’s write a rig control program with pySerial.

import serial
ser = serial.Serial('/dev/ttyUSB0', 19200, timeout=1)

for freq_khz in range(567,1449,3):
	khz    = freq_khz         % 10
	khz10  = freq_khz //   10 % 10
	khz100 = freq_khz //  100 % 10
	mhz    = freq_khz // 1000 % 10

	set_freq = b'\xfe\xfe\x80\xe0\x05\x00' \
			+bytes([16*khz         ])      \
			+bytes([16*khz100+khz10])      \
			+bytes([          mhz  ])      \
			+b'\x00\xfd'
	ser.write(set_freq)
	data1 = ser.read(18) # not 17 to raise timeout
	
	get_Smeter = b'\xfe\xfe\x80\xe0\x15\x02\xfd'
	ser.write(get_Smeter)
	data2 = ser.read(16)

	print(freq_khz, int( data2.hex()[26:30] ))
ser.close()

A simple program to scan the AM band and to record the signal strength.

The stations are, from left to right, NHK-1, NHK-2, AFN, and TBS.