Richard Polivka, N6NKO wrote:
<snip>
1) Fixed position. If the vehicle drops below a certain threshold speed,
call it STOP SPEED, we send out a quick burst of packets, say three to
five , to show the speed coming to zero for at least two packets.
I'm not sure we would want to do this, because every time you come to a
red light, you'd be going through this procedure. Some parts of the
country can't take that. Maybe ONE packet would be OK.
2) Moving mode. Me sees three possibilities here: A) fixed time
beaconing; B) Fixed distance beaconing; C) Speed based beaconing. I
would prefer speed based beaconing. Instead of having threshold points,
I would make the time change linear. Have an X-Y formula: X being speed;
Y being distance. Both end points on both axes are settable. At slower
speeds, you usually are working city streets. This would require more
transmissions because of the Urban Canyon issue and there are more
opportunities to radically change course. This would avoid the big
position jump on a track where you look at a map and see someone halfway
across the county changing directions.
The HamHUD used to send extra beacons in the event it didn't receive a
digi repeating it's own signal. It was taken out, I think because of
other people complaining about channel congestion, but I'm not 100% sure
of that -- it's been several years.
3) Dealing with turns. This seems to be a sore spot - corner pegging. We
only have a max data rate of 1 secoud out of most GPS units. So what I
would do is modify the sending rate based on the degrees turned and
instead of using a lookup table, I would use maybe cos^2 or cos^3 of the
angle change as the modfier. Modify from the current beaconing rate down
to 1 sec beaconing at >= 90 degrees. Here in Wisconsin, U-turns are
legal so those would have to be covered.
Now if I have covered old ground, forgive me. These are just thoughts.
When I first got started with the HamHUD, I tried and tried to do
perfect corner pegging, but I was never succesful. The problem being
that, in a 90-degree turn at an intersection, you need one set of
parameters, but in a 90-degree sweeper at 70 MPH, you need an entirely
different set of parameters. I don't think slope is enough to get it
right. I used to get 2 or 3 position packets sent out in the sweepers,
and while I could make adjustments to reduce that, it generally messed
up the intersections.
The other problem that I though I was seeing, but no one else agreed,
was if I came to, say, a 20-degree bend in the road and I was travelling
65 MPH, I did NOT get a position packet sent out. I think I was told
that, at those speeds, almost all the beacons are done by timing and not
by turning.
In the end, I just set everything to the default values and forgot
about it.
7 3
Earl
--
Earl Needham KD5XB
Clovis, New Mexico DM84jk
ZUT
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