time setting for satellite data

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KC0TNH
Posts: 4
Joined: Tue Jul 13, 2021 10:58 pm

time setting for satellite data

Post by KC0TNH » Sun Oct 24, 2021 9:28 pm

Does anyone know how to PERMANENTLY set the time in both the dm1801 and the gd77, for use in the satellite settings? it's a bit of a pain to re-set the time each time the rig is powered on .... besides the fact it does not actually take the full gps coordinates that is..

Thanks

KC0TNH

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F1RMB
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Location: Grenoble, France

Re: time setting for satellite data

Post by F1RMB » Sun Oct 24, 2021 9:35 pm

Hi,

https://github.com/LibreDMR/OpenGD77_Us ... md#suspend

What do you mean by " .... besides the fact it does not actually take the full gps coordinates that is" ?

73
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Daniel

VK3KYY
Posts: 7478
Joined: Sat Nov 16, 2019 3:25 am
Location: Melbourne, Australia

Re: time setting for satellite data

Post by VK3KYY » Mon Oct 25, 2021 9:54 pm

KC0TNH wrote:
Sun Oct 24, 2021 9:28 pm
Does anyone know how to PERMANENTLY set the time in both the dm1801 and the gd77, for use in the satellite settings? it's a bit of a pain to re-set the time each time the rig is powered on .... besides the fact it does not actually take the full gps coordinates that is..

Thanks

KC0TNH
Entering the position, which you refer to as GPS coordiunates, to more accuracy is pointless.

Changing the last digit of precision (0.001 of a degree) results in a change of around 2 seconds on AOS and LOS, if you change both lat and long. It changes the maximum elevation by 0.02 of a degree and makes no appreciable difference to the duration.

The orbital elements of the satellites aka Keppler data, is not available to anywhere near that precision, because the position of the satellites can't be tracked to that degree of accuracy.

BTW. We don't compensate for altitude either, becuase changes to altitude also make very little difference to the prediction calculations


Bear in mind this is a hand held radio, and the satellite function is not intended to replace a PC based tracking system.

Also please be aware at several commercial satellite tracking apps are necessarily accurate and don't say where they get the keps from and also what algorithm is used to do the predictions.

Try verifying the predictins from the firmware with a variety of sources eg AMSAT's own online prediction page.

KC0TNH
Posts: 4
Joined: Tue Jul 13, 2021 10:58 pm

Re: time setting for satellite data

Post by KC0TNH » Sat Oct 30, 2021 3:35 am

Surprisingly I figured that with a handheld ... as to having to re-set the time and date each power-on of the rig is a 'bit tedious' shall we say, as to the gps coordinates in either rig it will not take a negative number, therefore it is only good for a different hemisphere than the one that I am resident of...

CANNOTbe changed to east or west and is quite difficult even in the n/s settings.!

VK3KYY
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Location: Melbourne, Australia

Re: time setting for satellite data

Post by VK3KYY » Sat Oct 30, 2021 5:51 am

KC0TNH wrote:
Sat Oct 30, 2021 3:35 am
CANNOTbe changed to east or west and is quite difficult even in the n/s settings.!
https://github.com/LibreDMR/OpenGD77_Us ... ion-screen


The radio hardware does not have a real time clock, or GPS. Workaround for real time clock is as previously describe by F1RMB

https://github.com/LibreDMR/OpenGD77_Us ... md#suspend

UA0LMC
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Joined: Thu Oct 01, 2020 6:09 am
Location: Vladivostok, Russia

Re: time setting for satellite data

Post by UA0LMC » Sun Oct 31, 2021 7:15 am

VK3KYY wrote:
Sat Oct 30, 2021 5:51 am
The radio hardware does not have a real time clock, or GPS. Workaround for real time clock is as previously describe by F1RMB

https://github.com/LibreDMR/OpenGD77_Us ... md#suspend
BTW, what do you think of hardware mods?
I understand these mods won't be done by everybody, as some fine soldering skills are required - but it should provide a great deal of extra functionality.

So, I'd like to know your opinion, firmware-wise, is it worth it?
As for hardware - I could (or at least I could try to) implement this in my dm1801.

For now I'm exploring the following options:
1. To use MK22 built-in RTC.
As far as I can see in my dm1801, pins 28, 29 and 30 (XTAL32, EXTAL32 and VBAT raspectively) are left floating, as per datasheet requirement when unused.

The mod is to add a small 32K crystal, a bunch of capacitors, and something to power VBAT directly from the radio battery - i.e. a HT7133 voltage regulator with it's 5uA quiescent current. We should go well under 1mA in power-off mode after this mod.

For reference: now my dm1801 draws about 16mA in suspend mode, compared to average of 24mA in standby at Eco level 3 - which makes the suspend quite useless in terms of power saving.

2. GPS receiver integration.
As for the receiver itself, the only viable option I've found at the moment is sim33ela. It has an embedded antenna and it's pretty small, so I hope it will be easier to physically integrate it into the radio.

As for MCU connection, the bare minimum is only UART_RX pin (because software UART is not the thing you want to do). The combination of UART_RX, UART_TX and one GPIO to suspend the GPS should work for almost any possible config. The question is if there any unused UART pins are available.

VK3KYY
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Location: Melbourne, Australia

Re: time setting for satellite data

Post by VK3KYY » Sun Oct 31, 2021 11:06 pm

UA0LMC wrote:
Sun Oct 31, 2021 7:15 am
VK3KYY wrote:
Sat Oct 30, 2021 5:51 am
The radio hardware does not have a real time clock, or GPS. Workaround for real time clock is as previously describe by F1RMB

https://github.com/LibreDMR/OpenGD77_Us ... md#suspend
BTW, what do you think of hardware mods?
I understand these mods won't be done by everybody, as some fine soldering skills are required - but it should provide a great deal of extra functionality.

So, I'd like to know your opinion, firmware-wise, is it worth it?
As for hardware - I could (or at least I could try to) implement this in my dm1801.

For now I'm exploring the following options:
1. To use MK22 built-in RTC.
As far as I can see in my dm1801, pins 28, 29 and 30 (XTAL32, EXTAL32 and VBAT raspectively) are left floating, as per datasheet requirement when unused.

The mod is to add a small 32K crystal, a bunch of capacitors, and something to power VBAT directly from the radio battery - i.e. a HT7133 voltage regulator with it's 5uA quiescent current. We should go well under 1mA in power-off mode after this mod.

For reference: now my dm1801 draws about 16mA in suspend mode, compared to average of 24mA in standby at Eco level 3 - which makes the suspend quite useless in terms of power saving.

2. GPS receiver integration.
As for the receiver itself, the only viable option I've found at the moment is sim33ela. It has an embedded antenna and it's pretty small, so I hope it will be easier to physically integrate it into the radio.

As for MCU connection, the bare minimum is only UART_RX pin (because software UART is not the thing you want to do). The combination of UART_RX, UART_TX and one GPIO to suspend the GPS should work for almost any possible config. The question is if there any unused UART pins are available.
You would need to build your own version of the firmware to support whatever changes you make to your radio.

I don't have time to work on functionality for custom hardware, and I would not be able to include your code submissions, because it would be impossible for me to test whether they worked, as I won't be modifying my radio as the risk of me damaging the radio during the modification is too high.

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