I am trembling from exhaustion in the Terrascope room. Today was a hard day.
Yesterday was not nearly as bad. I'm going to blog about it first before I forget:
Met with Dr. Chan yesterday. He gave me lots of good advice about the setup of the system, such as never to keep the routers and non-weatherproof electronic equipment outside, even in a weatherproof box. Also, to keep moisture out of the attachment between the antenna mount pole (probably steel) and the grounding wire (copper), we should seal it in with epoxy resin to keep it from becoming a galvanic cell and corroding. (We bought this at Home Depot today.) Instead of mounting the antenna on top of the roof, we should mount it on a pole clamped firmly to the side of the building. Also, with 0.7 km of testing distance and 7 km of goal distance (a factor of 10), we should look for 20 dB of margin (difference between the signal strength/gain of our link and the minimum sensitivity) when we do the 0.7 km test. Since each 100 ft Ethernet cable attenuates the signal about 24 dB, if it works at all with a 100 ft Ethernet cable, that should qualify.
Our only real test that day was between Tang and the MIT West Parking Garage (~0.7 km). Ben was there to help carry things, which made everything much easier. It worked fine with the window open, but just barely with it closed (Dr. Chan suggested there might be a metal coating on the glass). Ben told us about a website called speedtest.net, which tests the upload and download speed of your Internet connection, and we found that the broadcasted Ethernet connection speed at Tang was 6 Mbps/8 Mbps (upload/download or vice versa, don't remember) and the received connection speed at the garage was around 2-4 Mbps upload and download. We also tested the signal strength of the connection, which can be found as a number (in dB) on the "Main" page of the Bullet configuration utility AirOS, which you access by plugging the cable coming out of the LAN port of the POE injector into your computer and typing the IP address of the Bullet into the URL bar of a web browser. The signal strength with the 100 ft outdoor rated Ethernet cable was -69 dB (negative gain because we had net losses over the link, not gains). The strength with only a 25 ft non-outdoor Ethernet cable was -71 dB- no idea what to make of that. Maybe the outdoor Ethernet cable isn't so lossy because it's shielded. The sensitivity of our receivers is around -96 dB, so we have a good 17-dB margin, which almost meets Dr. Chan's 20-dB margin requirement even with the 100 ft Ethernet cable. We're good.
Then we scouted for places to test at longer distances. We checked out Vassar street (~1.5 km) from Stata to where Tang is, and MacGregor's lounge windows (which conveniently faced in the right direction). We also found E15's roof deck on the 6th floor, which looked out in the direction of both MacGregor and Tang. Planning is power.
Today:
I lost my mind in the heat.
An Ethernet cable was shredded. I'm going to have to learn to solder on new Ethernet cable heads as well as N-male and female heads onto LMR400 coax cable.
There was a success, and a failure (both unexplainable).
The first place we tested was a short-range test down the Stata block on Vassar street, maybe a hundred meters. I didn't realize until I got there with all the equipment that there were no Ethernet jacks on the ground floor near where I had to be. On the fly, I had to set up my MacBook to share its wireless Internet connection with the Bullet while halfway in and out the door with pedestrians flooding by all the time. It was mostly simple (you go to "Sharing" in System preferences, check the Internet Sharing box, and the settings are "Share Airport Connection" and "over Ethernet" or something like that), but the tricky part was that I had to reconfigure the Bullet to use DHCP rather than a static IP address. All I remember about that stressful moment was that I kept all the settings I'd had before, but set IP address in the Network tab to DHCP. It worked fine; full bars. Then I went back to disassemble everything, and realized that the 100-ft Ethernet cable was slowly being skinned by being squeezed between the bottom of the door and the no-slip doorway, and then the door sliding back and forth on top. The plastic jacket was torn to reveal the metal shielding underneath. :( People also apparently thought it was okay to ride their bikes over my Ethernet cable, even when I waved my hands and shouted not to when they were far enough to slow down. It wasn't okay. I almost cracked in the heat.
Speedtest.net said I had an upload speed of 45 Mbps, and a download speed of 60 Mbps on Stata's MIT wireless network. It said J had an upload/download speed of 1-3 Mbps, which was probably because of the damaged cable.
The second place we tested was between the 14th floor lounge of MacGregor tower and the MIT West Parking Garage. I reset the Bullet (because it wouldn't let me access it using the IP address while on DHCP- maybe I should have tried to find out what IP address my MacBook had assigned to it) and reconfigured it to use a static IP address. We got full bars, both through the glass window (thankfully uncoated with metal) and the mesh screen on the windows that opened. Success.
While I had a download speed of 93 Mbps and an upload speed of 65 Mbps, J had upload/download speeds of about 2-4 Mbps. The signal strength found on the Bullet configuration main page was -66 dBm.
The third test started at around 11 pm. We'd started testing at around 5. It simply took forever to move stuff around to the different locations. I'd found a shopping cart in MacGregor and had tried to use it to carry everything; it didn't work because the shaking of the cart on the bumpy ground shook the screws out of the antenna and the feed fell out. :( I was afraid the bumping would be bad enough to damage the electronics in the router and Bullet, so I took those out too after reassembling the antenna as best I could in the middle of Memorial Drive (with the copious extra screws, nuts, and washers provided by ZDA Comm- go them!). By the time I got to my location in Stata, my hands were shaking and I was confused with tiredness. I thought the antenna was assembled incorrectly, so I reassembled it (incorrectly), then realized my mistake and re-did it correctly. Then I re-mounted the huge 3-ft wide 24 dBi monstrosity- a difficult job for a single tired person. It took a long time, and J sadly had to wait out at her location in the heat for me to finish (I'd had to help carry her stuff over at the Tang end of Vassar before coming to set mine up). Then I reset the Bullet, and tried configuring it again to use DHCP. I was apparently unsuccessful, because half an hour went by and we had four bars of signal, but no Internet service on J's end. There was apparently an error message pertaining to configuration. I reset and reconfigured the Bullet again, but the same error message appeared. :( I'm not sure what went wrong, but I will try again tomorrow starting with the configuration for static IP on the broadcasting Bullet (which I definitely got right). We will also probably not need this function in TZ of making the Bullet get Internet through a MacBook, but it'd be a backup plan. I'll also need to call Ubiquiti tech support about this not-being-able-to-access-configuration-when-Bullet-using-DHCP problem.
We had Greek pizza in the Terrascope room at around 1 AM. Maybe I like olives now.
I'll post my detailed conceptual drawings of the setup tomorrow (which I did while getting my glasses fixed), as well as some good things we found out about the actual locations in TZ. Like the GPS coordinates, and thanks to Google Earth (<3<3!), the elevation profile of the land across the line of sight! Which is looking fantastic, btw.
-E
Yesterday was not nearly as bad. I'm going to blog about it first before I forget:
Met with Dr. Chan yesterday. He gave me lots of good advice about the setup of the system, such as never to keep the routers and non-weatherproof electronic equipment outside, even in a weatherproof box. Also, to keep moisture out of the attachment between the antenna mount pole (probably steel) and the grounding wire (copper), we should seal it in with epoxy resin to keep it from becoming a galvanic cell and corroding. (We bought this at Home Depot today.) Instead of mounting the antenna on top of the roof, we should mount it on a pole clamped firmly to the side of the building. Also, with 0.7 km of testing distance and 7 km of goal distance (a factor of 10), we should look for 20 dB of margin (difference between the signal strength/gain of our link and the minimum sensitivity) when we do the 0.7 km test. Since each 100 ft Ethernet cable attenuates the signal about 24 dB, if it works at all with a 100 ft Ethernet cable, that should qualify.
Our only real test that day was between Tang and the MIT West Parking Garage (~0.7 km). Ben was there to help carry things, which made everything much easier. It worked fine with the window open, but just barely with it closed (Dr. Chan suggested there might be a metal coating on the glass). Ben told us about a website called speedtest.net, which tests the upload and download speed of your Internet connection, and we found that the broadcasted Ethernet connection speed at Tang was 6 Mbps/8 Mbps (upload/download or vice versa, don't remember) and the received connection speed at the garage was around 2-4 Mbps upload and download. We also tested the signal strength of the connection, which can be found as a number (in dB) on the "Main" page of the Bullet configuration utility AirOS, which you access by plugging the cable coming out of the LAN port of the POE injector into your computer and typing the IP address of the Bullet into the URL bar of a web browser. The signal strength with the 100 ft outdoor rated Ethernet cable was -69 dB (negative gain because we had net losses over the link, not gains). The strength with only a 25 ft non-outdoor Ethernet cable was -71 dB- no idea what to make of that. Maybe the outdoor Ethernet cable isn't so lossy because it's shielded. The sensitivity of our receivers is around -96 dB, so we have a good 17-dB margin, which almost meets Dr. Chan's 20-dB margin requirement even with the 100 ft Ethernet cable. We're good.
Then we scouted for places to test at longer distances. We checked out Vassar street (~1.5 km) from Stata to where Tang is, and MacGregor's lounge windows (which conveniently faced in the right direction). We also found E15's roof deck on the 6th floor, which looked out in the direction of both MacGregor and Tang. Planning is power.
Today:
I lost my mind in the heat.
An Ethernet cable was shredded. I'm going to have to learn to solder on new Ethernet cable heads as well as N-male and female heads onto LMR400 coax cable.
There was a success, and a failure (both unexplainable).
The first place we tested was a short-range test down the Stata block on Vassar street, maybe a hundred meters. I didn't realize until I got there with all the equipment that there were no Ethernet jacks on the ground floor near where I had to be. On the fly, I had to set up my MacBook to share its wireless Internet connection with the Bullet while halfway in and out the door with pedestrians flooding by all the time. It was mostly simple (you go to "Sharing" in System preferences, check the Internet Sharing box, and the settings are "Share Airport Connection" and "over Ethernet" or something like that), but the tricky part was that I had to reconfigure the Bullet to use DHCP rather than a static IP address. All I remember about that stressful moment was that I kept all the settings I'd had before, but set IP address in the Network tab to DHCP. It worked fine; full bars. Then I went back to disassemble everything, and realized that the 100-ft Ethernet cable was slowly being skinned by being squeezed between the bottom of the door and the no-slip doorway, and then the door sliding back and forth on top. The plastic jacket was torn to reveal the metal shielding underneath. :( People also apparently thought it was okay to ride their bikes over my Ethernet cable, even when I waved my hands and shouted not to when they were far enough to slow down. It wasn't okay. I almost cracked in the heat.
Speedtest.net said I had an upload speed of 45 Mbps, and a download speed of 60 Mbps on Stata's MIT wireless network. It said J had an upload/download speed of 1-3 Mbps, which was probably because of the damaged cable.
The second place we tested was between the 14th floor lounge of MacGregor tower and the MIT West Parking Garage. I reset the Bullet (because it wouldn't let me access it using the IP address while on DHCP- maybe I should have tried to find out what IP address my MacBook had assigned to it) and reconfigured it to use a static IP address. We got full bars, both through the glass window (thankfully uncoated with metal) and the mesh screen on the windows that opened. Success.
While I had a download speed of 93 Mbps and an upload speed of 65 Mbps, J had upload/download speeds of about 2-4 Mbps. The signal strength found on the Bullet configuration main page was -66 dBm.
The third test started at around 11 pm. We'd started testing at around 5. It simply took forever to move stuff around to the different locations. I'd found a shopping cart in MacGregor and had tried to use it to carry everything; it didn't work because the shaking of the cart on the bumpy ground shook the screws out of the antenna and the feed fell out. :( I was afraid the bumping would be bad enough to damage the electronics in the router and Bullet, so I took those out too after reassembling the antenna as best I could in the middle of Memorial Drive (with the copious extra screws, nuts, and washers provided by ZDA Comm- go them!). By the time I got to my location in Stata, my hands were shaking and I was confused with tiredness. I thought the antenna was assembled incorrectly, so I reassembled it (incorrectly), then realized my mistake and re-did it correctly. Then I re-mounted the huge 3-ft wide 24 dBi monstrosity- a difficult job for a single tired person. It took a long time, and J sadly had to wait out at her location in the heat for me to finish (I'd had to help carry her stuff over at the Tang end of Vassar before coming to set mine up). Then I reset the Bullet, and tried configuring it again to use DHCP. I was apparently unsuccessful, because half an hour went by and we had four bars of signal, but no Internet service on J's end. There was apparently an error message pertaining to configuration. I reset and reconfigured the Bullet again, but the same error message appeared. :( I'm not sure what went wrong, but I will try again tomorrow starting with the configuration for static IP on the broadcasting Bullet (which I definitely got right). We will also probably not need this function in TZ of making the Bullet get Internet through a MacBook, but it'd be a backup plan. I'll also need to call Ubiquiti tech support about this not-being-able-to-access-configuration-when-Bullet-using-DHCP problem.
We had Greek pizza in the Terrascope room at around 1 AM. Maybe I like olives now.
I'll post my detailed conceptual drawings of the setup tomorrow (which I did while getting my glasses fixed), as well as some good things we found out about the actual locations in TZ. Like the GPS coordinates, and thanks to Google Earth (<3<3!), the elevation profile of the land across the line of sight! Which is looking fantastic, btw.
-E
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