[Hackrf-dev] Fwd: nbfm

[Scott Davis]

Sent from my iPad

Begin forwarded message:

> From: Scott Davis <scottk5ta at gmail.com>
> Date: December 23, 2015 at 8:32:39 PM MST
> To: Cinaed Simson <cinaed.simson at gmail.com>
> Subject: Re: [Hackrf-dev] nbfm
> 
> 
> Sent from my iPad
> 
> -Scott
> 
>> On Dec 23, 2015, at 1:11 AM, Cinaed Simson <cinaed.simson at gmail.com> wrote:
>> 
>> Hi - what parameters would I need for NBFM transmit to ensure the
>> channel bandwidth on HackRF One is 15 kHz?
> 
> You would need to limit max deviation to 4kHz.  See:
> 
> http://www.n6nmz.net/sharkk/nbfmmath.htm
> 
>> Is Tau the transmission error? And for Tau = 75u is this equal to 75 Hz?
> 
> No, tau is the time constant (in microseconds) of the pre-emphasis audio filter.  See discussion here:
> 
> http://www.dspconcepts.com/sites/default/files/Modules/BasicAudioFloat32/Doc/EmphasisFilter.html
> 
>> In the example I copied, the Max Deviation was was set to 5k - would
>> setting Max Deviation to 4k be enough?
> 
> Yes -- see above.
> 
>> Any help would be appreciated.
>> 
>> -- Cinaed
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