From 789b0ad2d10a5274af798c3a1c45f8ee5a27eedc Mon Sep 17 00:00:00 2001
From: "Matthias P. Braendli" <matthias.braendli@mpb.li>
Date: Sat, 12 Dec 2020 16:10:12 +0100
Subject: Move to 6MHz IF

---
 freqplan.py | 26 ++++++++++++--------------
 1 file changed, 12 insertions(+), 14 deletions(-)

(limited to 'freqplan.py')

diff --git a/freqplan.py b/freqplan.py
index 9272c41..e01e6e5 100644
--- a/freqplan.py
+++ b/freqplan.py
@@ -1,39 +1,37 @@
 #!/usr/bin/env python3
 #
-# OUTDATED
-# This document is outdated because the VHF LO is not generated
-# externally
 
 from fractions import Fraction
 from math import floor
 
 xtal = 25
+PLLa_mult = 35
 
 print()
-print("# 116MHz and 4.915 MHz on PLLa")
+print("# 6000.694 - 2.200 kHz on PLLa")
 
-PLLa = xtal * 32
-print(f"PLLa = xtal * 32 = {PLLa} MHz")
+PLLa = xtal * PLLa_mult
+print(f"PLLa = xtal * {PLLa_mult} = {PLLa} MHz")
+
+if PLLa < 600 or PLLa > 900:
+    print(f"Error PLL {PLLA} out of bounds")
 
 # x/y = a + b/y
 # a = floor(x/y)
 # b = x - (a * y)
 
-f1 = 116
-a = floor(PLLa / f1)
-b = PLLa - (a * f1)
-div1 = Fraction(b, f1)
-print(f"CLK1: f1 = PLLa / ({a} + {div1.numerator} / {div1.denominator}) = {f1}")
-
-f2 = 4.91521
+f2 = (6000.694 - 2.200) / 1000
 a = floor(PLLa / f2)
 b = PLLa - (a * f2)
 div1 = Fraction(round(b * 10000), round(f2 * 10000))
 print(f"CLK2: f2 = PLLa / ({a} + {div1.numerator} / {div1.denominator}) = {f2}")
 
+VHF_LO = 114.285 # Fixed XTAL
+BAND_EDGE_LOW = 144 - VHF_LO
+BAND_EDGE_HIGH = 145 - VHF_LO
 
 print()
-print("# VFO between 23 and 25 MHz on PLLb")
+print(f"# VFO between {BAND_EDGE_LOW:6.6} and {BAND_EDGE_HIGH:6.6} MHz on PLLb")
 
 def calculate(frequency):
     divider = floor(900000000 / frequency) # Calculate the division ratio. 900,000,000 is the maximum internal
-- 
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