techdaemon | Audience Mode with Caddx Vista is terrible (Main & Audience side by side) @techdaemn | Uploaded January 2020 | Updated October 2024, 1 minute ago.
Best viewed at 1440p.
This is a Beta95x with Caddx Vista air unit, at 700mW. HQ mode.
Main goggles on the left, Audience mode goggles on the right.
Stock omnis all around on both goggles.
As you can see, the main goggles look great. Signal strength is high, latency varies little, bitrate is high. Audience mode is dreadful, from pretty much the moment of launch. Notice that the link stats for audience mode looks almost identical to the main goggles, but any time the latency rises above minimum (which I think indicates lost packets + retries), the image is degraded.
Here's my hypothesis on why.
Main goggles + regular DJI air unit use a combination of retry requests/re-transmissions to recover lost packets, and MIMO+CDD (same data stream is transmitted on both VTX antennas with a small delay between them to create signal redundancy). Audience mode goggles can't ask for retries and probably don't hear those that are sent anyway, but they can still see the dual CDD streams so the quality is ok, but gets bad quickly if a lot of packets are lost.
But Vista only has one Tx antenna so it cannot do MIMO+CDD. Main goggles can still do retries which you see in the variable latency, but audience mode goggles can't, and they only see a single data stream, so any lost packet immediately results in a degraded video signal, which can take a long time to recover from.
You'll notice that generally the video is worse when going straight away or toward home, and best when going perpendicular to path to home. That's consistent with the horizontal antenna orientation on the Beta95X. Going away or coming home, we're flying in the nulls. Appears that main goggles retry mechanism is enough to handle that, but it must be losing a few packets pretty much all the time.
DJI, please give us a real HDMI compatible video output option. Using the $750 Smart Controller as an HDMI dongle (next firmware update) is not acceptable.
Best viewed at 1440p.
This is a Beta95x with Caddx Vista air unit, at 700mW. HQ mode.
Main goggles on the left, Audience mode goggles on the right.
Stock omnis all around on both goggles.
As you can see, the main goggles look great. Signal strength is high, latency varies little, bitrate is high. Audience mode is dreadful, from pretty much the moment of launch. Notice that the link stats for audience mode looks almost identical to the main goggles, but any time the latency rises above minimum (which I think indicates lost packets + retries), the image is degraded.
Here's my hypothesis on why.
Main goggles + regular DJI air unit use a combination of retry requests/re-transmissions to recover lost packets, and MIMO+CDD (same data stream is transmitted on both VTX antennas with a small delay between them to create signal redundancy). Audience mode goggles can't ask for retries and probably don't hear those that are sent anyway, but they can still see the dual CDD streams so the quality is ok, but gets bad quickly if a lot of packets are lost.
But Vista only has one Tx antenna so it cannot do MIMO+CDD. Main goggles can still do retries which you see in the variable latency, but audience mode goggles can't, and they only see a single data stream, so any lost packet immediately results in a degraded video signal, which can take a long time to recover from.
You'll notice that generally the video is worse when going straight away or toward home, and best when going perpendicular to path to home. That's consistent with the horizontal antenna orientation on the Beta95X. Going away or coming home, we're flying in the nulls. Appears that main goggles retry mechanism is enough to handle that, but it must be losing a few packets pretty much all the time.
DJI, please give us a real HDMI compatible video output option. Using the $750 Smart Controller as an HDMI dongle (next firmware update) is not acceptable.
