Hi Mike, On 27/12/2015 13:28, Michael Black wrote: > The manual says split keeps the audio "in the range 1500 to 2000" > which isn't quite true. > > Really keeps it 1500-2179. That's correct. The manual is in terms of dial frequencies and signal frequencies based on the convention that the nominal frequency of a JT65 or JT9 signal is the lowest tone frequency. > > An offset of 1999 leaves the frequency as-is so the upper end of the > JT65 bandwidth is 2179. Bandwidth and nominal frequency are different concepts. > > Is that the intent? Or should the split adjustment be changed? The split is adjusted in 500 Hz steps which is convenient and supported on every rig we have seen so far. Note that several rigs have a minimum step size of 10Hz, some 100Hz. > > Are there any rigs that cut off below 2200 Hz? We are talking about Tx bandwidth here, the majority of rigs when set to USB/DATA-USB/DIGI-U/... do not have adjustable Tx bandwidth. Not that I am aware of when using default settings although a few rigs may be adjusted to reduce Tx bandwidth and shift the Tx passband. Those JT9+JT65 users using split may make adjustments to reduce their Tx bandwidth to ~1kHz centred at ~1800Hz above the suppressed carrier frequency but there should only be a small advantage which would be better obtained by making sure the Tx audio is clean in the first place.
Conversely, those with rigs that support the so-called ESSB transmit mode should be aware that using it defeats one of the key features of using split Tx in that the first few harmonics in the base audio domain will then be within the extended up to 6kHz SSB Tx passband. The most common issue related to this is that modern Yaesu rigs have a default DATA-USB configuration that shifts the dial frequency and pass band for Tx and Rx up from the normal SSB values. This results in incorrect dial frequency for WSJT-X operation and therefore spots are incorrect along with filtering out JT65 signals at the bottom of the HF sub-bands. Yaesu rig owners should set the DATA-DIAL and DATA-SHIFT menu parameters (some rigs use different terminology) both to zero for correct operation with WSJT-X. Those with SDR rigs that support 4Khz plus Tx bandwidths can avoid using split if they are careful about maintaining a clean signal. The use of digital audio throughout should allow audio harmonic free transmit signals in this case. 73 Bill G4WJS. ------------------------------------------------------------------------------ _______________________________________________ wsjt-devel mailing list wsjt-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/wsjt-devel
