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Mr.RC-Cam

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About Mr.RC-Cam

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    RC-Cam Mentor

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    USA
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    R/C, FPV, Embedded Programming, Electronic Design.

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  1. I would do a careful visual inspection for broken/burnt components and soldered joint problems. Then I'd check all the voltage regulators for proper output voltage. If these simple steps didn't help solve the problem then I wouldn't spend any more time on it. It seems it is important for you to repair it. Unfortunately success will be unlikely without an accurate schematic, RF test equipment, and access to the often difficult to procure Chinese semiconductors.
  2. Normally the MCU would control the front panel LED/LCD readout and handle the user input controls. I don't know if your device has these things since the information you posted is sparse. I don't see a typical RF synthesizer IC on your board. These are often 16 pin IC's (TSA5520 is popular) with a nearby 4MHz XTAL and EEProm. So perhaps your MCU is a custom device that includes the synthesizer function. Or maybe your board has an unusual 20 pin synthesizer IC (and it isn't a MCU as I thought). I can only guess at these details since I don't have your hardware in my hands. It's really up to you to reverse engineer the circuitry and do further research.
  3. My confidence is high that it is a MCU. Due to the location of the 8MHz Xtal the chip's pin-out seems to be similar to a TK68HC05J1A or something like it. But identifying the exact part number would require you to do more research. The nearby 8-Pin IC is likely to be a EEProm. Most of the low-end Chinese microcontrollers have poor code protection that can be disabled. So it's not unusual for Chinese goods producers to obscure the MCU's part number. They think tricks like that will make it more difficult to copy the code, but it's mostly wishful thinking. So why do it? Labor costs are low in China, so taking the time to grind-off some part numbers is common practice by them regardless of any real benefit.
  4. It appears to be a microcontroller because of the proximity of the 8MHz Xtal. There's nothing to be gained by determining the exact microcontroller part number. Because you'll need the proprietary firmware that is flashed into it.
  5. The earth below your feet is a hard RF reflector. So 5.8GHz multipathing will still occur even when you fly high. But every flying location is different; So perhaps start with linear antennas and then upgrade to CP if you experience too much multipathing interference at your field. A few years ago ImmersionRC redesigned the UNO5800 and started using their NWM662JRX NexWavRF module. It has the Richwave Rx chip. Their original UNO and DUO designs had the Airwave chip based Rx module, which only has -85dBm sensitivity. ImmersionRC was a late user of the Richwave Rx chip. Long after the success of the RX5808 (which uses Richwave chip) they took notice and started using it too. There are many suppliers that clone RX5808 modules and other variants. Quality can vary. Two identical vRx's may have different performance. So like many Chinese made FPV products, you have to buy and try.
  6. 5.8GHz FPV will be more reliable with CP antennas due to an increase in RF multipathing. You can use RHCP or LHCP; Both the vTx and vRx will need to be the same polarization (don't mix RHCP with LHCP). Most modern 5.8GHz vRx's use the Richwave Rx chip, so -90dBm sensitivity is common. But variations in build quality can affect the actual sensitivity. Advertised sensitivity that is better than -90dBm is probably wishful thinking.
  7. Typical recommendations will depend on the FPV video link frequency. 900MHz, 1.3GHz, 2.4GHz, or 5.8GHz?
  8. Applying a similar mod to the A/B (non-diversity) outputs would double-terminate the vRXs' video signals. Unfortunately this would reduce the diversity's video level.
  9. Good to hear the mod is working for you. Thanks for reporting.
  10. I understand that the attenuator is internally built into the new ImmersionRC meter. Unlike their original meter it is not a separate part. The 50ohm/75ohm difference will not be a problem.
  11. Look for DiY vRx OSD applications by searching for projects like this: https://dronegarageblog.wordpress.com/2016/01/20/arduino-5-8ghz-rx5808-module-open-source-fpv-receiver/
  12. Thanks for reporting you solved the problem.
  13. That's a lot of things that are contributing to your problem. Too bad our FPV gear makers aren't more careful with the video signal levels. The symptoms include indications that you have a severe video emphasis compatibility issue or other modulation problem. That often occurs when mixing vTx and vRx brands. Since the goggles have a Nexwave vRx module (an ImmersionRC development), there's a chance that a ImmersionRC Nexwave branded vTx would improve your rebroadcasting link's sync and colorburst levels. First on the list is to restore the overall (full-white) signal level to 1Vpp. Maybe a different resistor in the UNO will provide a cheap workaround. Otherwise, a video amp with a gain of about 1.6X is needed on the UNO's video out. Still a bandaide, but might get you back on your feet. - Thomas
  14. 1. This link will give basic information on how to measure the video: https://www.rc-cam.com/forum/index.php?/topic/2825-using-the-50-digital-scope-to-measure-video-levels/ 2. If you disconnect the rebroadcasting vTx from the Uno the Uno's output will increase 2X. With the rebroadcasting vTx removed you must install a 75 ohm resistor on the Uno vRx's video signal to properly terminate it. Then you can measure the video level of the Uno. 3. The video example looks like multipathing interference to me. That will happen a LOT inside a building. Take everything outside, away from all structures, and then test it. If the video is more stable then the problem indoors involved multipathing.
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