invalid_always is applied to random payloads

[danielrichman]

This isn't actually a bug, more of a UI issue.

See https://github.com/ukhas/genpayload/blob/master/genpayload.html#L501

My explanation on IRC, from earlier today, after uXABEN had invalid_always on it and so wasn't appearing on the map:

16:05 < DanielRichman> genpayload asks "When without a lock, this payload sends:"
16:06 < DanielRichman> - other
16:06 < DanielRichman> - this format
16:06 < DanielRichman> - a certain value in the gps lock field
16:06 < DanielRichman> - lat lon as 0,0
16:06 < DanielRichman> now invalid_always is added in the 'this format' case
16:06 < DanielRichman> i.e., "this is the format it sends if it has no lock, and if it does have a lock it sends a differnet format'
16:07 < DanielRichman> the intention was to support stuff like $$CALLSIGN,,,some other temperature data*XXX
16:07 < DanielRichman> i.e., blank fields - literally a different format
16:07 < DanielRichman> or $$A1,!!:!!:!!,!!.!!!!!!,!!!.!!!!!!!,temperature data etc.*XX
16:07 < DanielRichman> in which case you would match the !!! fields with a constant string, and have a second format for normal parsing
16:07 < DanielRichman> anyway
16:07 < DanielRichman> that's an aside
16:08 < DanielRichman> the problem is that 'When without a lock this payload sends this format' could be misinterpreted
16:08 < DanielRichman> indeed, if you have a general format that is sent for both strings with lock and strings without a lock, the statement 'when without a lock this payload sends this format' is true

Now the UI does show the text "Any latitude longitude or altitude, if present, will be marked invalid. Other parsed data, like temperature, can still be used and plotted." but it's off to the side and a bit less prominent than it perhaps should.

I'm thinking of reworking that section of the form to start with a quick explanation of the point of different formats/format matching (similar to explanation above), and then present 3 radio choices:

• The payload always sends this format, and if there's no lock:
  • select [sends latlon 0,0; sends a gps_lock field]
• The payload has a different format when it doesn't have a lock
  • checkbox [it's this format]
• Other (with a note or something like, come chat to us, parsing no lock sentences is good and you totally want to do it, etc.)