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{ "url": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/XK4FPRNAOG3ZB7IKQB2ME5FEOCNHMTFC/", "mailinglist": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/", "message_id": "[email protected]", "message_id_hash": "XK4FPRNAOG3ZB7IKQB2ME5FEOCNHMTFC", "thread": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/thread/O7DDIMF22HA6QJRC5R4ARD6LTZ3NXWUY/", "sender": { "address": "alex (a) kr1st.com", "mailman_id": "295825cc45654832a81730906beec2aa", "emails": "https://mailman.amsat.org/hyperkitty/api/sender/295825cc45654832a81730906beec2aa/emails/" }, "sender_name": "[email protected]", "subject": "[AMSAT-BB] Re: LVB Tracker firmware with multiple calibration points?", "date": "2021-03-21T21:18:03Z", "parent": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/O7DDIMF22HA6QJRC5R4ARD6LTZ3NXWUY/", "children": [], "votes": { "likes": 0, "dislikes": 0, "status": "neutral" }, "content": "Hi Jarda, \n\nThank you for your note and sharing your thoughts. \n\nYour assumptions are correct. Even though the circuit of the controller\nof the G-450XL (which rather different than the G450(A) and the G5500\nbtw) makes it less suitable to control it with a LVB type tracker, it is\nrather clever in that it compensates for an aging potentiometer inside\nthe rotor. Indeed it uses a DC motor to display the direction. \n\nI did look at those manuals before and that's how I noticed the\ndifferences. Actually, the board inside the G-450XL controller\nidentifies it as a KP-650XL. \n\nThe potentiometer in the rotator and the one in the controller are part\nof a bridge circuit. When the rotator moves and the value of the pot\nmeter in the rotator changes, the bridge gets unbalanced and a voltage\ngets generated that will drive the motor in the controllor until the pot\nmeter in the controller balances the bridge again. So it's a synchronous\nsystem. \n\nI did add an opamp circuit between where I pick off the indicator\nvoltage from the pot meter inside the controller and the tracker. That\ndid not make things linear. I think it's the two transistors near the\nbridge that start to play a role once the rotator passes 180 degrees\nthat make things non-linear. I'm not even sure why they are there. \n\nThe condition you mentioned is indeed occuring. The voltage varies from\n1.54-4.44 for 0-360 degrees. I have a PIC programmer and a few extra\nPIC's on order. I think if I can manage to add calibration points for\nevery 30 degrees it will work OK. \n\n73, \n\n--Alex KR1ST \n\nOn 2021-03-20 08:59, ok2gz wrote:\n\n> Hi Alex,\n> I guess that Your trouble with LVB tracker is made by the circuity of G450 azimuth sensor and connection between G450 and LVB.\n> LVB tracker was developed for G5500 rotator, which (as I guess) has different internal circuity. \n> I Guess also, that g450 Azimuth rotaror uses DC motor in the control box to show position in the scale 0-360 degrees and internal circuity serves for liear driving DC motor inside (as position indicator).\n> Manual for GS232 says, that Yaesu tracker GS232 (similar to LVB) works with : \n> \n> G800,G1000,G2800 \n> \n> G400,G500,G550 \n> \n> G5400,G5500, G5600 rotators.. Please look for three manuals (pdf files on the web):\n> 1. Your G450\n> 2. G5500\n> 3. GS232 Yeaesu satellite tracker, where is lot of importatn informations\n> \n> G5500 has sensor constructed with 500 ohm potentiometer feeded by 6V source and regulated by OZ amplifier into the 0-5V limit. For good linearity is very important, that potentiometer - sensor cannot be loaded with low impedance - reason for use the OZ amplifier ( high input impedance for potentiometer, low output impedance for AD converter input!). Otherwise the linearity will go down. \n> LVB tracker expect, that input voltage from sensor is in interval 0 - 5V for azimuth 0 to 360 degrees (or 450 degrees with G5500).\n> LVB uses 8bit PIC microcontroller with 10 bit AD converter - 1024 positions for 0-5V (with 5V AD reference voltage used in LVB). \n> \n> When occur condition: AZ = 0 degrees : 1.5V signal \n> AZ = 360 degrees : 4.0 V signal\n> then You get smaller resolution (half against 0-5V)\n> And yet - without calibration it is quite wrong.\n> \n> LVB also expect to make the calibration, which is very well described by G6LVB and also in GS232 manual.\n> During power-up You must press the button, the LVB internal code of PIC16F876 skip into the calibration procedure. Then You get on LCD display exact hints what to do - as described by G6LVB. \n> Yet exist commands for calibration via the serial port terminal. They were developed by G6LVB and does not fit description in GS232 manual..\n> I hope it can help You with Your rotator. \n> \n> 73 \n> \n> Jarda ok2gz \n> \n> [1]\n> Virus-free. www.avg.com [1]\n> \n> -----------------------------------------------------------\n> \n> Sent via AMSAT-BB(a)amsat.org. AMSAT-NA makes this open forum available\n> to all interested persons worldwide without requiring membership. Opinions expressed\n> are solely those of the author, and do not reflect the official views of AMSAT-NA.\n> Not an AMSAT-NA member? Join now to support the amateur satellite program!\n> \n> View archives of this mailing list at\n> https://mailman.amsat.org/hyperkitty/list/[email protected]\n> To unsubscribe send an email to amsat-bb-leave(a)amsat.org\n> Manage all of your AMSAT-NA mailing list preferences at https://mailman.amsat.org\n \n\nLinks:\n------\n[1]\nhttp://www.avg.com/email-signature?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=emailclient\n\n\n", "attachments": [ { "email": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/XK4FPRNAOG3ZB7IKQB2ME5FEOCNHMTFC/", "counter": 2, "name": "attachment.html", "content_type": "text/html", "encoding": "utf-8", "size": 6437, "download": "https://mailman.amsat.org/hyperkitty/list/[email protected]/message/XK4FPRNAOG3ZB7IKQB2ME5FEOCNHMTFC/attachment/2/attachment.html" } ] }