Cannot stream video from Axis 241AQ to Powerstation2

[khanna]

I have upgraded from a smartbridges Airpoint pro to a Powerstion2.
Before I upgraded my system, it worked okay just slow.

Now, I cannot stream video from the station. I can ping the all the on the station devices.

The set-up is as follows:
I have two PowerStation 2s with os 3 in bridge mode. One is configured as a station and the other is an AP.

On the station side, I have two Axis 241AQ video servers, one serial to Ethernet convertor, and an Ethernet intercom system.

On the AP side, I have the rest of the network with my router.

The network is all on the same network segment - 192.168.0.X, net mask 255.255.255.0, 1st DNS 192.168.0.2 (the internal dns server), 2nd DNS is to the ISP. router at 192.168.0.168.

When I at local to the Stations side I can login and access the video server via a web browser and see video and the control panel for the server. At the AP, side I can login, but cannot see the video or access the control panel.


What do I need to look at or do to get the video to stream?

[UBNT-keba]

My suggestion is to use WDS modes (STA WDS/ AP WDS)

[khanna]

I have tried the the station and ap in WDS mode. I am still not able to get streaming video form the Axis equipment.

[WHT]

If possible, I would take a laptop over to the place where you feed the cameras to the Powerstation and see if you can get it to work with a wired connection.

[khanna]

I have taken a laptop to the site.

Locally at the station location I can access all the systems and they function correctly. I can access the web through the station->AP->Intenet.

I have a Microsoft Small Business Server that I access, but I cannot Log onto a client machine throught the Remote Web Access.

Is there a DNS or routing problem with the ps2 station->AP->local network?

[WHT]

You can easily determine if its a DNS issue. Try using the actual IP address. If that doesn't work, its more than a DNS issue. If it does work, then it is a DNS issue.

[khanna]

I can ping using the IP address. I can scan the network and find the IP addresses for the devices at the station side.

The odd problem is that my old wireless bridge worked correctly with the axis video servers. The only change between now and then is the new wireless ps2 equipment.

[rconaway]

Just of of curiousity, how much bandwdith are the cameras using? Also, can you log into the web interface on the Axis 241?

[khanna]

I am unable to gauge the video thoughput from the site since the packets will not past for the site to the AP.

I can log into the axis video servers. I cannot get the video stream or the menus to display.

[rconaway]

do an ftp site reboot on the camera

ftp to the camera
login
literal
site reboot

see if that fixes your problem.

[liukuohao]

I have upgraded from a smartbridges Airpoint pro to a Powerstion2.
Before I upgraded my system, it worked okay just slow.

Now, I cannot stream video from the station. I can ping the all the on the station devices.

The set-up is as follows:
I have two PowerStation 2s with os 3 in bridge mode. One is configured as a station and the other is an AP.

On the station side, I have two Axis 241AQ video servers, one serial to Ethernet convertor, and an Ethernet intercom system.

On the AP side, I have the rest of the network with my router.

The network is all on the same network segment - 192.168.0.X, net mask 255.255.255.0, 1st DNS 192.168.0.2 (the internal dns server), 2nd DNS is to the ISP. router at 192.168.0.168.

When I at local to the Stations side I can login and access the video server via a web browser and see video and the control panel for the server. At the AP, side I can login, but cannot see the video or access the control panel.


What do I need to look at or do to get the video to stream?

Hi Khanna,

I was hoping that PowerStations can support video streaming, it seems that
it does not or capable of handling video streaming.

First of all, please find out bit rate of your Axis video server is using for

MPEG4 streaming- This streaming is recommended for wireless
transimission. MPEG4 is more compressed than MJPEG.

Note:
MJPEG streaming- This streaming is NOT recommended because it takes
too much bandwidth in wireless transmission.


I think for 4 channels of MPEG4 streaming is about 12Mbps max for 4
channels at D1 resolution (not very sure about this, but you must
confirm this bit rate value on the Axis sever manual). So when you have 2
servers you will have 24Mbps max. By the way, have you try set the video
server at constant bit rate instead of variable bit rate?

Next you must ask whether your bandwidth of the wireless link can sustain
30 Mbps.(add another 5Mbps on top) over 300 metre .

Also you must ask whether your PowerStation has enough buffer to prevent
intermittent latency due to packet loss during transmission.

Can a PS with EXT model solve this problem since 2 extra external antennas
are added and therefore 1 antenna will perform receive and the other will
perform transmit which will become FULL duplex, instead only 1 antenna
doing the transmit and receive for a normal PS model? Will this improve
throughput and increase the bandwith?


Mike can you help out in answering the above for Khanna?
I would like to know as well.
:)

[rconaway]

I'm not sure what D1 resolution is. For video we usually use the term CIF, 2CIF, 4CIF, etc... CIF=320x240. Depending on compression, the bandwidth ranges from 80K to 600K at that resolution at 30fps.

We have several of these running and will have 5 more set up in about 2 weeks. I have total confidence this works. However, you have to keep the bandwidth within the connected speed of the AP's. With MPEG-4, you can have variable bandwidth. We have pushed them to 25Mbps over a PTP NS5 connection but that's the absoluted max. In reality, assuming 100% CCQ and 54Mbps modulation, I wouldn't go past 20Mbps. Keep in mind that the auto ACK might also be changing bandwidth based on connection issues.

Video is obviously more time sensitive than data so you have to make sure your wireless structure is sound before you start shooting video across it. The NS and Powerstations work fine with video if they are set up correctly.

[WHT]

I'm playing with the H.264 at the moment with my cameras.

[liukuohao]

Hi rconaway & WHT,

Thanks for your comment.

What I am interested to know is:

If a video server which is able to output of 12Mbps(max.) of MPEG4 streaming
from 4 analogue cameras. Can a pair of PowerStation5 running on wireless
bridging able to support smooth video streaming?

Thanks.
:o

[liukuohao]

Just add in something for my previous thread.

The link only 150 metres apart between two PS5?
Has anyone try it before?

WHT, if you are playing H264 network camera.
There should not be any problem of getting streaming to work acrosss
wireless link because the bandwith is very very low compares to MPEG4
streaming.

Thanks
:o

[liukuohao]

Hi everyone,

Can some verify the information below is correct?.
Please.......

In order to find out whether a pair of PS5 can sustain a 12Mbps video
streaming over a wireless bridge link. I did some maths on my own.

I went ahead to calculate the Free Space Loss for distance of 120 metres
across the both PS5 in Line of sight arrangement (no object blocking the
signal path, like trees):

Free Space Loss
= 40 + 20Log(distance in metres)
= 40 + 20Log(120)
= approx. 82dB (only a rough estimate)

I choose the minimum Receive Sentivity is –91dBm @ 12Mbps from the PS5
data sheet. So, this is the minimum receiving signal level for a PS5 at the
receiving end to support 12Mbps data transmission.

Next, I calculate the total gain of the link:

A= Transmit power = 26 dBm @ 12Mbps.
B= Integrated Panel Antenna Gain = 22 dBi of PS5(A)
C= Signal Loss in cable in PS5(A) = -2 dB
D= Integrated Panel Antenna Gain = 22dBi of PS5(B)
E= Signal Loss in cable of PS5(B) = -2dB

So, the total gain = A+C+B+D+E = 26-2+22+22-2 = 66dB

Signal Level at one radio link PS5(A) to PS5(B)
= Total gain – Free Space Loss
= 66- 82
= -16dB

So since both ends are using the same wireless CPE, then the signal level at
one radio link from PS5(B) to PS5(A) is also = -16dB

Now that I know the signal level is –16 dB which more than minimum
Receive Sentivity of –91dB. Then I conclude that wireless link
between the two PS5s, can support the video streaming of 12Mbps,
with no problems.

In fact according to the PS5 data sheet, if receiving signal level is at
–16dB(which is more than –74dB) the can support up till 54Mbps of data
transmission.

Thanks in advance.
:o

[WHT]

No, its incorrect.

Good effort on your part, it shows you know how to think things through. But you have three errors in your calculations.

1) The Friss constant is incorrect, it should be 32.44
[edited - oh wait, 40 might be correct if you are using meters. 32.44 is for kilometers. I'd have to check the conversion constant as I don't know it off the top of my head.]
[edited again - see next post about that "40" constant]
2) You are missing the frequency component in your Friss calculation.
3) Due to wireless overhead, your data speed has to be at least twice that of your expected data throughput.

[rconaway]

WHT, I did some testing last week and we found that overhead was about 80% higher for MPEG-2 and MPEG-4. 6.1Mbps streams, 10.3Mbps wireless. Of course, this is using the tools in the radio. Dude gave us even lower numbers. Didn't have a switch with me to measure the LAN ports but we are doing that in about 2 weeks again with the cable system. What is weird though is that we can push 23Mbps (according to the built-in bandwidth tool in an Axis camera) with 2 cameras total and not have a problem. Somebody is not telling the truth there.

Liukuohao, the answer is that it will work if you keep your bandwidth in check. 12Mbps@26dBm gives you a maximum of 5Mbps of usable bandwidth which means your streams need to be a Max of 3Mbps total aggregate bandwidth according to my testing and 2 according to WHT. I tend to believe his numbers until I get a switch on the Lan ports.

[WHT]

according to WHT. I tend to believe his numbers I believe in peer review and am willing to make corrections in my assumptions when empirical evidence shows different.

So far...peer reviews (discounting Ron's commentary) of my assumptions appear to be pretty close to everyone's observations.

Disclaimer: Matthew 6:2 does not apply here.
"When you give alms, for example, do not blow a horn before you in synagogues and streets like hypocrites looking for applause."

[WHT]

liukuohao...

Ok, I see what you did. It appears you mis-applied the correction factor and thus didn't factor in the frequency.

The actual Friss Equation:
20 x log10 x d (meters)+ 20 x log10 x f (Hz) + 20 x log10 x (4л/c)

20 x log10 x (d meters) = 20 x log10 x (120)
20 x log10 x (d meters) = 20 x (2.079)
20 x log10 x (d meters) = 41.58

20 x log10 x (f Hz) = 20 x log10 x (5,800,000,000)
20 x log10 x (f Hz) = 20 x (9.764)
20 x log10 x (f Hz) = 195.3

20 x log10 x (4л/c) = 20 x log10 x ((12.56)/299,790,000)
20 x log10 x (4л/c) = 20 x log10 x (.0000000419)
20 x log10 x (4л/c) = 20 x -7.378
20 x log10 x (4л/c) = -147.6

Total free space diversion loss is:
41.6 + 195 – 148 = 88.6 dB

Since you didn't factor in the frequency, that "40" constant you used appears to have been written for 2.4 GHz.

----------------------------------

Now lets figure you total system gain:

For PS5 22 dBi internal antenna (no line losses) at 36 Mbps data speed (you could use 24 Mbps, but 36 Mbps will give you more leeway).

24 dBm TPO + 22 dBi ant - 87 dB loss + 22 dBi ant + 83 dBm RX sens. = 64 dBm.

That will be 19 dB over your RX sensitivity, so you will have a 19 dBm system operating margin (SOM or fade margin).

----------------------------------

Taking the data speed up to 54 Mbps for a 27 Mbps throughput, will leave you with only a 6 dB SOM. Which might be all right for such a short link.

[WHT]

If you use the UBNT online free space loss calculator
http://www.ubnt.com/support/freespace.php

It will give you 89.274 dB loss compared to my 88.6 dB loss because I rounded off numbers.

If you add the numbers in my post using more decimal digits, you will get 89.28.

[WHT]

Rory...Will my spread sheet help?

http://telecomanddata.com/video_compression_compare.png

[rconaway]

These numbers seem really high. Again, I'm using the bandwidth caclulator in the Axis camera and the real-time info in the SkyPilot and nanos we did the testing with. However, we did testing with no motion, some motion, full-motion. Even with full motion in MPEG-4 with 50% compression (Axis compression specs), 10fps, we only see mid 250Kbps. Under low motion, we see see 80-150Kps. I think the compression rate is different than what you are using or my systems wouldn't even come close to working. Another issue is that we using all UDP. I'm sure the camera is correct but the radio will show a lower number.

[WHT]

I'm using a calculator from JVSG.com $19
http://www.jvsg.com/

[WHT]

oh wait...I'm using the CCTV version. The IP version looks different.

[edited] I just downloaded the IP version and after I installed it, it shows it registered to me. Maybe I already have it. It has a lot more H.264 sections. appears it might be an upgrade from my year before last version.

Hay...for $19...go for it.

[rconaway]

Axis has a tool on their website that we use also. I'll check it out.

[WHT]

That reminds me...of an article I did about Axis's disengenuality comparing analog to IP. I'll post it on my website later this week.

[rconaway]

One thing I don't like about axis is the .5 to 2 second delay on broadcasting. I'm assuming it's due to their buffer but I think their codec needs work. I also think their processors are underpowered. Turn compression down and it delays more.

[liukuohao]

liukuohao...

Ok, I see what you did. It appears you mis-applied the correction factor and thus didn't factor in the frequency.

The actual Friss Equation:
20 x log10 x d (meters)+ 20 x log10 x f (Hz) + 20 x log10 x (4л/c)

20 x log10 x (d meters) = 20 x log10 x (120)
20 x log10 x (d meters) = 20 x (2.079)
20 x log10 x (d meters) = 41.58

20 x log10 x (f Hz) = 20 x log10 x (5,800,000,000)
20 x log10 x (f Hz) = 20 x (9.764)
20 x log10 x (f Hz) = 195.3

20 x log10 x (4л/c) = 20 x log10 x ((12.56)/299,790,000)
20 x log10 x (4л/c) = 20 x log10 x (.0000000419)
20 x log10 x (4л/c) = 20 x -7.378
20 x log10 x (4л/c) = -147.6

Total free space diversion loss is:
41.6 + 195 – 148 = 88.6 dB

Since you didn't factor in the frequency, that "40" constant you used appears to have been written for 2.4 GHz.

----------------------------------

Now lets figure you total system gain:

For PS5 22 dBi internal antenna (no line losses) at 36 Mbps data speed (you could use 24 Mbps, but 36 Mbps will give you more leeway).

24 dBm TPO + 22 dBi ant - 87 dB loss + 22 dBi ant + 83 dBm RX sens. = 64 dBm.

That will be 19 dB over your RX sensitivity, so you will have a 19 dBm system operating margin (SOM or fade margin).

----------------------------------

Taking the data speed up to 54 Mbps for a 27 Mbps throughput, will leave you with only a 6 dB SOM. Which might be all right for such a short link.

Hi WHT,

Thank very much for clarifying and showing my mistake :)

There is one thing I don't understand is equation below:

24 dBm TPO + 22 dBi ant - 87 dB loss + 22 dBi ant + 83 dBm RX sens. = 64 dBm.

What I expect is this:

24dB+22dB-FreeSpaceLoss+22dB > ReceiveSensitivity

In other words, I can simplify above further by using the equation below:

Total_Gain(one_way) > ReceiveSensitivity

If ReceiveSensitivity = -83dB

and..........................

If the Total_Gain(one_way) =
24+22-88.6(as derived above)+22dB = -20.6dB

So, Total_Gain(one_way) = -20.6dB which is more than the
ReceiveSensitivity of the receiving PS5 = -83dB.

Therefore radio signal from one direction to the other end can be successfully
received by PS5. So the link can be established without any problem.

And the margin = 83-20.6 = 62.4

Since the transmitting power reaching to the receiving PS5 = -20.6dB,
then can I expect the transmission is:
54Mbps but actual speed = 27Mbps - 5Mbps for overhead = 22Mbps ???

27Mbps is half of 54Mbps since 802.11g antenna is running at half duplex
operation which only perform receive or transmit at one time and not both
simultaneously

Am I right?

Thanks.

[WHT]

You're doing good so far. Rearranging a formula to gain a better understanding of the math is a good technique, i.e.:
amps = volts / resistance
resistance x amps = volts

24 dBm TPO + 22 dBi ant - 87 dB loss + 22 dBi ant + 83 dBm RX sens. = 64 dBm SOM (fade margin). 64 dBm is how much signal you are delivering to the receiver that is signal above and beyond the minimum level to recover data.
So, Total_Gain(one_way) = -20.6dB which is more than the
Receive Sensitivity of the receiving PS5 = -83dB. That is correct.

And the margin = 83-20.6 = 62.4 That is jumbled. Your actual MARGIN is derived below.

24 + 22 - 87 + 22 + 83 = 64 is the above and beyond level of the RX sensitivity.

64 dB - 83 dBm RX = -19 dBm is the difference between the RX threshold and the above and beyond level. This is your MARGIN. See below:
That will be 19 dB over your RX sensitivity, so you will have a 19 dBm system operating margin (SOM or fade margin).
---------------
27Mbps is half of 54Mbps since 802.11g antenna is running at half duplex
operation which only perform receive or transmit at one time and not both
simultaneously Correct, but the actual throughput is limit by the CPU, so its really closer to around 22 Mbps.

[liukuohao]

Hi WHT,

Thank you very very much for answering your queries so far!!!!!! :D Without
people like you I don't know who I can turn to for help.

[rconaway]

Oh man, don't encourage him. The man is naming farm animals after Ubiquti radios now. I think a vacation from this website is in order. Maybe we can get Ron to take over for a while. I'm a bad man. Once I get my claws in a running gag....

[WHT]

So I suggested UBNT start a certification program....Like Certified Ubiquiti Systems Service, but Rory thought his Certified Ubiquiti Network Technician would get more attention.

Yeah...he was on a roll this morning.

[WHT]

Oh man, don't encourage him. The man is naming farm animals after Ubiquti radios now.
http://forum.ubnt.com/forum/viewtopic.php?t=9790

[rconaway]

ROFL - Oh man, I'm in trouble now. All I know is that Cicso certs and support forums aren't anywhere near as colorful. Good thing I didn't submit my network technical specialist idea. All I know is that I should get some Brownie Points towards my Guru status soon or my acronyms are really going to get bad.

I think you should change WHT's status to:

Certified Omniscient Ubiquiti Gura and Radio Specialist (as a sign of respect for his age)

[WHT]

Oh....the Marconi thing again......phftttttttttt