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Diffstat (limited to 'host/docs/usrp_b200.dox')
| -rw-r--r-- | host/docs/usrp_b200.dox | 31 |
1 files changed, 28 insertions, 3 deletions
diff --git a/host/docs/usrp_b200.dox b/host/docs/usrp_b200.dox index 6ee2f3445..9d3550b98 100644 --- a/host/docs/usrp_b200.dox +++ b/host/docs/usrp_b200.dox @@ -36,15 +36,40 @@ images: The master clock rate feeds the RF frontends and the DSP chains. Users may select non-default clock rates to acheive integer decimations or -interpolations in the DSP chains. The default master clock rate defaults -to 32 MHz, but can be set to any rate between 5 MHz and 61.44 MHz. +interpolations in the DSP chains. The clock rate can be set to any value +between 5 MHz and 61.44 MHz (or 30.72 MHz for dual-channel mode). +Note that rates above 56 MHz are possible, but not recommended. The user can set the master clock rate through the usrp API call uhd::usrp::multi_usrp::set_master_clock_rate(), or the clock rate can be set through the -device arguments, which many applications take: : +device arguments, which many applications take: uhd_usrp_probe --args="master_clock_rate=52e6" +The property to control the master clock rate is a double value, called `tick_rate`. + +\subsection b200_auto_mcr Automatic Clock Rate Setting + +The default clock rate setting is to automatically set a clock rate +depending on the requested sampling rate. The automatic clock rate selection +is disabled when either `master_clock_rate` is given in the device initialization +arguments, or when uhd::usrp::multi_usrp::set_master_clock_rate() is called. + +Note that the master clock rate must be an integer multiple of the sampling +rate. If a master clock rate is chosen for which this condition does not +hold, a warning will be displayed and a different sampling rate is used internally. + +Nevertheless, there are multiple valid values for the master clock rate +for most sampling rates. The auto clock rate selection attempts to use +the largest possible clock rate as to enable as many half-band filters +as possible. Expert users might have cases where a more fine-grained +control over the resampling stages is required, in which case manually +selecting a master clock rate might be more suitable than the automatic +rate. + +The property to dis- or enable the auto tick rate is a boolean value, +`auto_tick_rate`. + \section b200_fe RF Frontend Notes The B200 features an integrated RF frontend. |