To: The Miami Valley Mesh Alliance
The next MVMA meeting will be this Saturday, October 8th, at 9:30 am at the Bellbrook Amateur Radio Club (BARC) Clubhouse, located at Sugarcreek Elementary School, 51 South East Street, Bellbrook, OH 45305, Room 1, Lower Level.
Meeting Agenda: Meeting will be a discussion of current topics, to include:
- Introductions and Recent Achievements
- DARA Clubhouse Install
- Fairgrounds Mesh Install
- Other node locations… In the Works
- Filter Update
- Current Test Results
- AREDN – Ubiquiti M5 XW Board Solution
- Presentation: N8NQH- Cat5 vs Cat6 cable, and associated connectors.
- Presentation: AB8XA- Link Performance Measurements on Local Mesh
- Presentation: N8JJ on GPS Mobile
- The case for using dual polarity, MIMO Antennas with Rocket radios.
- Hardware demonstrations
Mesh Promo Video: The following is forwarded by Bob Dixon, of the Delaware Mesh club. Nice Promo. Now….. if we just had their scenery….. and their airborne drone camera….
Please call or write if you have any questions. If you no longer wish to receive MVMA emails, please reply to this email with that request.
To: The Miami Valley Mesh Alliance
There will be NO MVMA meeting this Saturday, September 10th. We will, instead, attempt a third install of the 2.4 omni node at the DARA Clubhouse (see below). The install party will gather at 8am at the Clubhouse.
The next MVMA meeting will be Saturday, October 8th, at 9:30 am at the Bellbrook Amateur Radio Club (BARC) Clubhouse, located at Sugarcreek Elementary School, 51 South East Street, Bellbrook, OH 45305, Room 1, Lower Level.
The Time Has Come, The Walrus said, to speak of ………… FILTERS! We have had several “learning experiences” using filters over the last two months. A summary of these experiences follows.
- When we installed the 2.4 Omni node at Miami Valley Hospital South, we found that the node receiver was being de-sensed by a paging transmitter, on 940 MHz, running high power (~200 watts) into a high gain antenna located about ten feet from our node antenna. When the pager transmitted, it effectively shut down the node receiver. The problem was corrected by installing a Chinese MicroStrip Band Pass Filter, as shown in the graphic below. The MicroStrip filters are available on eBay for about $12. Tim Procuniar mounted the filter in a box, as shown in the graphic below (or attached); we installed the filter between the Bullet and the L-Com Omni Antenna, and it effectively fixed the de-sense problem.
- When we made the initial node installation at the DARA Clubhouse tower, we found that the 2.4 Node receiver was being de-sensed by the ATV Repeater, located on the same tower. The ATV repeater simulcasts on 421.25 MHz and 1258 Spectrum checks using a HackRF showed that there was no signal interference in the Node’s Channel -2 receive band; rather, the repeater transmitter signal strength appeared to swamp the Node receiver. We made a decision to install a filter on the DARA 2.4 Node.
- Before we could get the filter installed, the DARA Tower took a lightning strike which took out all of our installed equipment.
- We purchased more of the MicroStrip filters, and mounted them in similar fashion, in an all aluminum project box with type N connectors. Both Tim Procuniar, and Tom Holmes help “sweep out” the filters, to determine pass-band frequency limits, and insertion loss. The MicroStrip filters flunked the sweep tests, showing pass-band curves that looked nothing like what we observed previously with the unit installed at MVH-S. We determined that mounting technique was CRITICAL…. keeping exposed coax center conductors SHORT is important.
- At the same time, we acquired a new filter made by a Chinese company called Teletronics International Inc. These 3-pole ceramic filters come pre-packaged with the connectors of your choice. They are sold by RFWirelessUSA.com, located in Maryland, for a cost of $71 each, plus S&H. We also “swept” these filters. They demonstrated excellent pass-band characteristics (which easily covered all of Channel -2 at 10 MHz bandwidth), with an insertion loss of about 3 db.
- We decided to do a performance comparison of the MicroStrip Filter, the Teletronics Filter, and no Filter, at the MVH-S Site. Data recorded at MVH-S is shown in the graphic below (or attached, depending on your email handler). We evaluated each filter by comparing received signal strength from N8NQH and WA8APB nodes, and the strength of the MVH-S signal received AT N8NQH, with and without a pager signal present.
- The bottom line… is that the Teletronics filter significantly outperformed the MicroStrip Both filters blocked the pager signal. Received signal strength measurements were about the same, with and without the pager signal present. However, At MVH-S, we saw a 5 to 8 db increase in receive sensitivity (signal strength), and at N8NQH, we saw an increased signal strength from MVH-S, of about 4 db, using the Teletronics filter, when compared to the MicroStrip unit. We noted that the Teletronics filter also dropped the noise floor, such that the Signal to Noise Ratio with the Teletronics was 28 db, which MATCHED the S/N ratio using no filter at all.
- We decided to suspend use of the MicroStrip filters, in favor of the Teletronics We also concluded that use of a band-pass filter should be standard practice at any location where our 2.4 Nodes will be co-located with other transmission systems (commercial towers, commercial roof-top sites, water tanks, ARRL Field Day, etc.).
- Last Saturday, Phil Verret and I attempted a re-install the 2.4 node with the Teletronics filter, at the top of the DARA tower (170 ft). All equipment was checked out on the ground. Unfortunately, we encountered two problems after install; one of the Cat5e lines opened, and while we had the Node on the air with power over Ethernet, we had no computer control of the node at the bottom of the wire. Worse…. we noted that the Filter N connector between the filter and the antenna failed. The male N connector literally came apart. The install was abandoned, and all equipment returned to the ground. On a positive note, we did successfully install a Microwave receiver link that provides back-up Internet from a P&R Tower to the DARA Clubhouse.
- It appears that a cast flange on the central barrel of the connector separated from the barrel. While we did not intentionally over-tighten the connector, nor impose lateral forces that would cause the connector to fail ….. something must have happened. We have been working with RFWirelessUSA, and they have graciously replaced the filter unit with the bad connector.
- So….. We are ready to work the DARA install again….. and plan to do so this Saturday, September 10th, starting at 8:00am weather permitting. Bruce Kress, KD8YWC and I will climb. If you are interested in participating in ground crew, please contact me by email, or the cell number below.
- We are investigating the possibility of purchasing filters custom tuned (or which we can custom tune) for Channel -2. We would go for a bandwidth of 20 to 30 Such filters would cost approximately $160 (manufacturer tunes) or $80 (we tune). It is not clear that we would realize an overall performance improvement by using the narrower filters, but somehow… I suspect the Filter Saga is not over yet.
L-Com Antennas: L-Com is once again offering their 2.4 GHz 15 dbi Omni HG2415U-PRO antennas for $45, plus $5 shipping, IF purchased in lots of 5 units. (Five antennas will cost $225 plus $25 S&H). If you have interest in participating in a group purchase of these antennas, please contact Moe Riggins, AB8XA, at firstname.lastname@example.org.
That’s all for now.
At this point, it appears the weather will not cooperate; rain is forecast for all day. Hence, we expect no Installation activities tomorrow.
Our rain date is next Saturday, 9 July, 9:00am.
In the unlikely event that the weather clears in early morning, and all is bright and beautiful…. we may attempt to reschedule the install for sometime tomorrow. If that occurs, I will advise all with another email in the morning. However, I do not expect that will come to pass……
Thanks to all who volunteered to support this activity!
The DARA Clubhouse Tower Mesh Install is scheduled for Monday, July 4th, starting at 9:00am. Rain date is Saturday, July 9th. Help is needed! Please contact Bill Curtice at number below, or Tim Procuniar N8NQH if you are able to support this work. I will provide updated plans in an email to all MVMA prior to the July 4th install date.
To: The Miami Valley Mesh Alliance
Confirming: The next MVMA meeting will be this Saturday, June 11th at 9:30am at the Bellbrook Amateur Radio Club (BARC) Clubhouse, located at Sugarcreek Elementary School, Room 1, Lower Level. The address is 51 South East Street, Bellbrook, OH 45305.
Welcome to the Miami Valley Mesh Alliance website.
2016 Dayton Hamvention is this coming May 20 – 22, 2016 at the HARA Arena 1001 Shiloh Springs Rd., Dayton, OH 45415.
Our Inside Exhibit booth is in the East Hall booth# 659.