removing the L-band gap on E4000

Jacek Lipkowski sq5bpf at lipkowski.org
Thu Nov 8 22:09:18 UTC 2012


Hello

I've tried to remove the L-band gap on my E4000 tuner by changing the 
divisors. Please see the patch below. I don't have a signal source to test 
today, so i'm not sure if it works, but the pll locks. I will try to test 
tomorrow.

Without my hack: E4K L-band gap: 1093 to 1233 MHz

With my hack:

sq5bpf at dellix:~/gnuradio/rtl-sdr/src$ ./rtl_test -t
Found 1 device(s):
   0:  ezcap USB 2.0 DVB-T/DAB/FM dongle

Using device 0: ezcap USB 2.0 DVB-T/DAB/FM dongle
Found Elonics E4000 tuner
Supported gain values (14): -1.0 1.5 4.0 6.5 9.0 11.5 14.0 16.5 19.0 21.5 
24.0 29.0 34.0 42.0
Benchmarking E4000 PLL...
[E4K] PLL not locked for 51000000 Hz!
[E4K] PLL not locked for 2186000000 Hz!
E4K range: 52 to 2185 MHz
E4K L-band gap: 0 to 0 MHz


Regards

Jacek / SQ5BPF



--- tuner_e4k.c.orig	2012-11-08 22:08:07.000000000 +0100
+++ tuner_e4k.c	2012-11-08 23:01:05.000000000 +0100
@@ -35,6 +35,7 @@
  /* If this is defined, the limits are somewhat relaxed compared to what the
   * vendor claims is possible */
  #define OUT_OF_SPEC
+#define HACKED_DIVISORS

  #define MHZ(x)	((x)*1000*1000)
  #define KHZ(x)	((x)*1000)
@@ -357,7 +358,14 @@
  	{KHZ(350000),	(1 << 3) | 1,	8},
  	{KHZ(432000),	(0 << 3) | 3,	8},
  	{KHZ(667000),	(0 << 3) | 2,	6},
-	{KHZ(1200000),	(0 << 3) | 1,	4}
+#ifdef HACKED_DIVISORS
+/* the original settings seem to be ripped from some Elonics driver,
+ * however changing them a bit removes the L-band gap 
+ * change this to a bit more then the end of your L-band gap --sq5bpf */
+	{KHZ(1270000),	(0 << 3) | 1,	3} 
+#else
+	{KHZ(1200000),  (0 << 3) | 1,   4}
+#endif
  };

  static int is_fvco_valid(uint32_t fvco_z)




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