Pulse Star II (first analog version)

[Jose]

Hopefully i know and understand how to use oscilloscope.
I measured exactly what's on my sketch that i drawn and posted previously.
What surprises and confuses me is only the "rest of time" in schedule, after the second sample and before the next TX pulse.
Dependable on position of Sampling Delay switch, between its 4 positions.
I expected cycles to be same length at all 4 positions. Or at least to rise up small amount of time, as main delay rises.
On contrary; position "1" with shortest main delay is having longest "spare time" till the next TX pulse!?
Quite opposite from what i expected.
Is it mandated by the analog circuitry and its limitations... or it was intentionally done like that, i can't tell.
Is it of any importance or not... also i can't tell.
Such long delays and wide pulses... probably is of less importance the "spare" (unused) time before the next TX pulse.
Whatever the truth; fact is it is interesting and uncommon. Unlike majority of PIs that we seen here so far.

The times are fine, if they are added in the same unit of time, "u s".
Which, makes sense, the frequency is maintained, they only move, proportionally according to the delay in the different positions.

[ivconic]

What else can you expect up there in Sweden?
Meteorites of course!
Decent number years ago i exchanged several friendly and educative (mostly for me) emails with Thomas Osterberg.
Man was meteorite hunter at the time.
You can strike a fortune faster with meteorites than with any kind of hoards.

[ivconic]

Thank you everyone for answers, this detector i will use mostly with big coils and mostly for finding hoards/other big targets. I don't know how you can use small coils/small delay inland because iron trash is killing me, especially where are signs of settlement (for what do you use small - ~30cm coil - other than find eg: known widespread hoard). If i want to go where is not trash/less targets meaning woods, my GT is deep enough. That is why i ask people who use the detectors, not only build or design them, i need insight from the field.

PS2 and 2x2m coil is probably overkill in most of the cases.
Suitable only for wide area leveled terrain with no trees, bushes and tall grass.
But PS2 and 1x1m coil, or 1x1.5m coil; would be quite alright for such use.
1x1m coil is even better because you can operate and handle it alone, on your own.
Standing inside the coil, carrying it on two belts on your shoulders.
Deep enough.
With Sampling Delay on "2", "3" and even "4" in case you search for extra large target.

[ivconic]

Hopefully i know and understand how to use oscilloscope.
I measured exactly what's on my sketch that i drawn and posted previously.
What surprises and confuses me is only the "rest of time" in schedule, after the second sample and before the next TX pulse.
Dependable on position of Sampling Delay switch, between its 4 positions.
I expected cycles to be same length at all 4 positions. Or at least to rise up small amount of time, as main delay rises.
On contrary; position "1" with shortest main delay is having longest "spare time" till the next TX pulse!?
Quite opposite from what i expected.
Is it mandated by the analog circuitry and its limitations... or it was intentionally done like that, i can't tell.
Is it of any importance or not... also i can't tell.
Such long delays and wide pulses... probably is of less importance the "spare" (unused) time before the next TX pulse.
Whatever the truth; fact is it is interesting and uncommon. Unlike majority of PIs that we seen here so far.

[ionut_mtb]

Thank you everyone for answers, this detector i will use mostly with big coils and mostly for finding hoards/other big targets. I don't know how you can use small coils/small delay inland because iron trash is killing me, especially where are signs of settlement (for what do you use small - ~30cm coil - other than find eg: known widespread hoard). If i want to go where is not trash/less targets meaning woods, my GT is deep enough. That is why i ask people who use the detectors, not only build or design them, i need insight from the field.

[Jose]

If I measure TX, channel 1 oscilloscope.
Delay first sample channel 2 oscilloscope, okay.
I think the timing of the first sample, along with the second sample, relative to the TX pulse, is what really matters.

[ivconic]

I'll check that again, i will perform another measurements.
I used different method of thinking.
Your is simpler and faster, just scope TX pulse and count time to next one.
I did much complicated (probably there is mistake).
I measured TX relative to 1. sample time.
Than 1. sample time relative to 2. sample time.
Than the end of 2. sample time to next TX.
While is much simpler only to scope TX and measure time between two TX pulses.
So i will do that tonight.

[Orbit]

That's strange?
How did you measure that?
Whole cycle: is TX - 1.delay - S_Y pulse - 2.delay - S_X pulse.....certain pause ... again next cycle TX - 1.delay - S_Y pulse - 2.delay - S_X pulse
Now, you shall measure the time from point where S_X pulse ends to the next appearance of TX pulse.
According to your graphic; that time from one TX pulse to another TX pulse is much shorter than what i measured last night?

Measured at the gate irf640 pulse width 100uS time between pulses 1.53ms , I measured with a digital oscilloscope there is certainly no mistake! When I calculated the period you measured you have a longer period therefore low time 100us high time 1.53ms = Period (T) 1.63ms

[ivconic]

I was not interested in time at all but here's just the transmitter time..[ATTACH]53589[/ATTACH]

That's strange?
How did you measure that?
Whole cycle: is TX - 1.delay - S_Y pulse - 2.delay - S_X pulse.....certain pause ... again next cycle TX - 1.delay - S_Y pulse - 2.delay - S_X pulse
Now, you shall measure the time from point where S_X pulse ends to the next appearance of TX pulse.
According to your graphic; that time from one TX pulse to another TX pulse is much shorter than what i measured last night?

[Jose]

It would be interesting to see the integrator you use to process sample pulses as wide as 275 us.

[Orbit]

I was not interested in time at all but here's just the transmitter time..

[eclipse]

25-300us is the primary delay for skipping small items. 300us is rather high I think you get natural small items rejection with large coils anyway but this also reduces the amount of useful signal which is processed further I wouldn't keep it, probably ~150us (max) seems a bit more useful in my view.

3.5ms to 6.5ms (dead period) shows quite a bit dead period.
I would place Sx pulse at the end of the cycle (right before the next TX cycle) this way you won't get reduced signal for large Tc targets or just add 1ms between Sx and Sy to have better response on really long Tc targets.

[ivconic]

I haven't measured the timings (no scope right now but from these graphs) TX width is 100uS (somewhat lower than expected ~200uS).
Sample Sy is the first sample with 25us-300us delay from TX. Sx is the second sample 250us after Sy. Sample widths are 275uS which is somewhat higher than expected (200us) but I guess it's OK. Frequency seems OK. If you want try to increase TX width up to 200us for better response on large targets. Timings are easily doable with MCU.

Correct.
Although i measured with oscilloscope and draw those early this morning (barely awake); i think i didn't make mistake.
So, what is confusing me are those long pauses between cycles.
Long and so different between choices from "1" to "4".

[eclipse]

I haven't measured the timings (no scope right now but from these graphs) TX width is 100uS (somewhat lower than expected ~200uS).
Sample Sy is the first sample with 25us-300us delay from TX. Sx is the second sample 250us after Sy. Sample widths are 275uS which is somewhat higher than expected (200us) but I guess it's OK. Frequency seems OK. If you want try to increase TX width up to 200us for better response on large targets. Timings are easily doable with MCU.

[ivconic]

Here comes the interesting part, which i don't understand quite well, will need clarification by someone more conversant: