Comments on: Frequency Hopping http://blog.strobotics.com.au/2007/11/19/frequency-hopping/ Where Photographer and Geek merge...... Sun, 18 Dec 2011 11:07:23 +0000 hourly 1 http://wordpress.org/?v=3.3.1 By: faizanbrohi http://blog.strobotics.com.au/2007/11/19/frequency-hopping/comment-page-1/#comment-1013 faizanbrohi Thu, 25 Feb 2010 16:05:08 +0000 http://blog.everythingrobotics.com/2007/11/19/frequency-hopping/#comment-1013 i get it , it depends on the bitrate , deviation and bandwidth , but how they are related , what is the formula for calculating in any frequency band. i get it , it depends on the bitrate , deviation and bandwidth , but how they are related , what is the formula for calculating in any frequency band.

]]> By: Stephen Eaton http://blog.strobotics.com.au/2007/11/19/frequency-hopping/comment-page-1/#comment-1012 Stephen Eaton Thu, 25 Feb 2010 03:57:10 +0000 http://blog.everythingrobotics.com/2007/11/19/frequency-hopping/#comment-1012 It all depends on the bit rate you select as the deviation and bandwidth are different for each datarate. The main thing is the bandwidth as deviation needs to be less than the bandwidth, so use bandwidth in your calc. <code> bps channels Dev(khz)BW (khz) @9600 60 75 134 @19200 52 75 134 @38400 45 90 200 @57600 37 105 270 @115200 29 180 340 Channel 9600 19200 38400 57600 115200 1 900.84 900.84 900.84 900.84 900.84 2 901.32 901.40 901.49 901.62 901.85 3 901.80 901.95 902.13 902.40 902.85 4 902.28 902.51 902.78 903.18 903.86 5 902.76 903.06 903.42 903.96 904.86 6 903.24 903.62 904.07 904.74 905.87 7 903.72 904.17 904.71 905.52 906.87 8 904.20 904.73 905.36 906.30 907.88 9 904.68 905.28 906.00 907.08 908.88 10 905.16 905.84 906.65 907.86 909.89 11 905.64 906.39 907.29 908.64 910.89 12 906.12 906.95 907.94 909.42 911.90 13 906.60 907.50 908.58 910.20 912.90 14 907.08 908.06 909.23 910.98 913.91 15 907.56 908.61 909.87 911.76 914.92 16 908.04 909.17 910.52 912.54 915.92 17 908.52 909.72 911.16 913.32 916.92 18 909.00 910.28 911.81 914.10 917.93 19 909.48 910.83 912.45 914.88 918.93 20 909.96 911.39 913.10 915.66 919.94 21 910.44 911.94 913.74 916.44 920.94 22 910.92 912.50 914.39 917.22 921.95 23 911.40 913.05 915.04 918.00 922.95 24 911.88 913.61 915.68 918.78 923.96 25 912.36 914.16 916.32 919.56 924.96 26 912.84 914.72 916.97 920.34 925.97 27 913.32 915.27 917.61 921.12 926.97 28 913.80 915.83 918.26 921.90 927.98 29 914.28 916.38 918.90 922.68 928.99 30 914.76 916.94 919.55 923.46 31 915.24 917.49 920.19 924.24 32 915.72 918.05 920.84 925.02 33 916.20 918.60 921.48 925.80 34 916.68 919.16 922.13 926.58 35 917.16 919.71 922.77 927.36 36 917.64 920.27 923.42 928.14 37 918.12 920.82 924.06 928.92 38 918.60 921.38 924.71 39 919.08 921.93 925.35 40 919.56 922.49 926.00 41 920.04 923.04 926.64 42 920.52 923.60 927.29 43 921.00 924.15 927.93 44 921.48 924.71 928.58 45 921.96 925.26 929.22 46 922.44 925.82 47 922.92 926.37 48 923.40 926.93 49 923.88 927.48 50 924.36 928.04 51 924.84 928.59 52 925.32 929.15 53 925.80 54 926.28 55 926.76 56 927.24 57 927.72 58 928.20 59 928.68 60 929.16 </code> It all depends on the bit rate you select as the deviation and bandwidth are different for each datarate. The main thing is the bandwidth as deviation needs to be less than the bandwidth, so use bandwidth in your calc.

bps channels Dev(khz)BW (khz)
@9600 60 75 134
@19200 52 75 134
@38400 45 90 200
@57600 37 105 270
@115200 29 180 340

Channel 9600 19200 38400 57600 115200
1 900.84 900.84 900.84 900.84 900.84
2 901.32 901.40 901.49 901.62 901.85
3 901.80 901.95 902.13 902.40 902.85
4 902.28 902.51 902.78 903.18 903.86
5 902.76 903.06 903.42 903.96 904.86
6 903.24 903.62 904.07 904.74 905.87
7 903.72 904.17 904.71 905.52 906.87
8 904.20 904.73 905.36 906.30 907.88
9 904.68 905.28 906.00 907.08 908.88
10 905.16 905.84 906.65 907.86 909.89
11 905.64 906.39 907.29 908.64 910.89
12 906.12 906.95 907.94 909.42 911.90
13 906.60 907.50 908.58 910.20 912.90
14 907.08 908.06 909.23 910.98 913.91
15 907.56 908.61 909.87 911.76 914.92
16 908.04 909.17 910.52 912.54 915.92
17 908.52 909.72 911.16 913.32 916.92
18 909.00 910.28 911.81 914.10 917.93
19 909.48 910.83 912.45 914.88 918.93
20 909.96 911.39 913.10 915.66 919.94
21 910.44 911.94 913.74 916.44 920.94
22 910.92 912.50 914.39 917.22 921.95
23 911.40 913.05 915.04 918.00 922.95
24 911.88 913.61 915.68 918.78 923.96
25 912.36 914.16 916.32 919.56 924.96
26 912.84 914.72 916.97 920.34 925.97
27 913.32 915.27 917.61 921.12 926.97
28 913.80 915.83 918.26 921.90 927.98
29 914.28 916.38 918.90 922.68 928.99
30 914.76 916.94 919.55 923.46
31 915.24 917.49 920.19 924.24
32 915.72 918.05 920.84 925.02
33 916.20 918.60 921.48 925.80
34 916.68 919.16 922.13 926.58
35 917.16 919.71 922.77 927.36
36 917.64 920.27 923.42 928.14
37 918.12 920.82 924.06 928.92
38 918.60 921.38 924.71
39 919.08 921.93 925.35
40 919.56 922.49 926.00
41 920.04 923.04 926.64
42 920.52 923.60 927.29
43 921.00 924.15 927.93
44 921.48 924.71 928.58
45 921.96 925.26 929.22
46 922.44 925.82
47 922.92 926.37
48 923.40 926.93
49 923.88 927.48
50 924.36 928.04
51 924.84 928.59
52 925.32 929.15
53 925.80
54 926.28
55 926.76
56 927.24
57 927.72
58 928.20
59 928.68
60 929.16

]]> By: faizanbrohi http://blog.strobotics.com.au/2007/11/19/frequency-hopping/comment-page-1/#comment-1011 faizanbrohi Wed, 24 Feb 2010 17:48:49 +0000 http://blog.everythingrobotics.com/2007/11/19/frequency-hopping/#comment-1011 how many channels can we achieve in the rfm12b , i have used the rfm12b-915 . i see its frequency ranges from 900 to 929 in 7.5Khz steps but have tested on two frequencies 914 and 922 , but there has to be band gap due to frequency deviation ,how much channels can i achieve ? . i will then move on to 433Mhz for greater range. but i think the channels will reduce. it has 2.5Khz steps. how many channels can we achieve in the rfm12b , i have used the rfm12b-915 . i see its frequency ranges from 900 to 929 in 7.5Khz steps but have tested on two frequencies 914 and 922 , but there has to be band gap due to frequency deviation ,how much channels can i achieve ? . i will then move on to 433Mhz for greater range. but i think the channels will reduce. it has 2.5Khz steps.

]]> By: Stephen Eaton http://blog.strobotics.com.au/2007/11/19/frequency-hopping/comment-page-1/#comment-1010 Stephen Eaton Wed, 24 Feb 2010 02:00:36 +0000 http://blog.everythingrobotics.com/2007/11/19/frequency-hopping/#comment-1010 I did some initial design work for a mesh using frequency hopping here if that's any help http://code.google.com/p/strobit/wiki/WidgetMesh I did some initial design work for a mesh using frequency hopping here if that’s any help

http://code.google.com/p/strobit/wiki/WidgetMesh

]]> By: Stephen Eaton http://blog.strobotics.com.au/2007/11/19/frequency-hopping/comment-page-1/#comment-1009 Stephen Eaton Wed, 24 Feb 2010 01:58:38 +0000 http://blog.everythingrobotics.com/2007/11/19/frequency-hopping/#comment-1009 this was the original link to the project from hackaday: http://hackaday.com/2007/11/17/spread-spectrum-freq-hopping-usb-rf-modem/ this was the original link to the project from hackaday:
http://hackaday.com/2007/11/17/spread-spectrum-freq-hopping-usb-rf-modem/

]]> By: Stephen Eaton http://blog.strobotics.com.au/2007/11/19/frequency-hopping/comment-page-1/#comment-1008 Stephen Eaton Wed, 24 Feb 2010 01:56:14 +0000 http://blog.everythingrobotics.com/2007/11/19/frequency-hopping/#comment-1008 bugger, looks like it's gone. Will try and track it down. bugger, looks like it’s gone. Will try and track it down.

]]> By: faizanbrohi http://blog.strobotics.com.au/2007/11/19/frequency-hopping/comment-page-1/#comment-1007 faizanbrohi Tue, 23 Feb 2010 16:33:06 +0000 http://blog.everythingrobotics.com/2007/11/19/frequency-hopping/#comment-1007 link not working link not working

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