Friday, August 21, 2015

Intel ATOM D525 Network Performance

I recently had the occasion to use a small Intel Atom D525 based Linux server to do some file transfers from one machine to another. I noticed that the file transfers were not very snappy, so I started to look closer at the issue. The Microtik switch that I'm using has a nice usage meter on each interface and I noticed that a single rsyc over ssh was only giving me 100-150Mb/s performance. Realizing that this was compressed and using the somewhat whimpy Atom CPU, I backed off to a minimal compression algorithm and ended up getting a modest improvement (200Mb/s). So, running 4 parallel rsyncs seemed to be the trick, but I seem to cap out around 5-600Mb/s:

The CPU seemed to hover around 40-50%, which was odd, I would have expected to see a higher percentage if my performance was capped.

I later tried NFS to see if that did the trick, but it too capped around 5-600Mb/s. The particular distribution of Linux I was using was Zentyal 3.5, but I also tried on an Ubuntu 14.04 Atom D525 system as well with the same results.

Just to make sure it wasn't something to do with the server I initiated a transfer from my desktop PC running Windows 7. You can see the server doesn't have any issues keeping up. In a later blog post I'll go into the ethernet switch I'm using and how changing the default queueing method affects performance in a positive manner.

The end result is that I wasn't able to push the Intel Atom D525 board beyond 5-600Mb/s. It could be an ethernet driver issue since the CPU didn't seem to be loaded beyond 50%, but I figured it would be an interesting datapoint to share. If anyone sees differently, please message me with your results.

Thursday, May 7, 2015

Android lockscreen image stuck?

I've been using a Samsung Galaxy S5 for about a year now. I don't really like it, and recently ran into another little annoyance that I'm fairly sure would *never* happen on an Apple device. I created an account and started listening to a book on my long commute to/from work. I notcied that Audible used the book image as the default lock screen image. Fine, whatever, but when Audible was closed the image remained. This was really annoying, as I couldn't change it even manually!

I googled for a fix, but nothing really came up that was useful. The suggestions mostly came in the form of "launch another streaming app and then lock the screen, that should undo it...". Well, that didn't work. Even when I closed all open apps it still didn't go away.

Then I discovered that even though I closed all the open apps it didn't really close. If I did the "pull-down" motion in touch-wiz there was an audible control applet still running. Once that control applet was closed, the problem went away. Very annoying, this is the lack of attention to detail that drives me nuts with Android. I'm likely going back to Apple just because I know it will do the right thing. It may not be quite as configurable, but the experience will be much more consistent.

Friday, August 3, 2012

Tropo the day before the contest!

This weekend is the UHF contest, and of course, we had a bit of tropo the nigh before! I missed most of it, even after N1ZZN texted me. I was busy watching "All the President's Men".

Anyhow, I ran downstairs and worked three stations: N4HB, KD8UD and KD4AA, all in FM17. I didn't hear any of the beacons, so this seemed like a very narrow path. The APRS map isn't detailed enough, but gives and ok representation.

Thursday, July 26, 2012

Massive Es 2M opening on 7/24/2012

I got home from work Tuesday, 7/24/2012, to an email from Bart, W9JJ, saying there was a 2M Sporadic E opening on 2M. I literally leapt from the couch and flew down the stairs to the shack. I turned the rig on and immediately heard AG4V in Tennessee, grid square EM55! I quickly worked him, just as he faded. That QSO was 1060 miles on 2M!

There were reports of guys working from New England all over the Memphis, TN area. The last two stations I heard were WB5AFY in TX and another station in AK. I wasn't able to work the Texas station, he was just too weak and he was saying the W2/W3's were S9+. He was about 4x2 here.

The best DX I've heard so far was Dave, K1WHS, working Al Ward, W5LUA in TX (FN43 to EM13, roughly 1500 miles).

I did manage to grab a screen shot of the APRS map before it faded into history:

Friday, July 20, 2012

CQ VHF WW Contest this weekend!

This weekend is the CQ VHF WW contest. Contest start is 1800 UTC (2pm EDT), end time is 2100 UTC Sunday (5pm EDT). This contest is 50MHz and 144MHz only, the rules can be found here.

I plan on operating a good portion of the weekend.

Dick Bean, K1HC, and his son Kevin, KB1EAN, will be roving up into some rare grids up in Maine. Here is the email he sent to the Morning 205 report:

I am planning a Rover effort up to Maine for the CQ WW VHF 
contest with my son, Kevin, KB1EAN.  
7/21: FN53 (Pemaquid Point), FN54 (overnight in Bangor)
7/22:  FN 54 (Bangor), FN64 (lunch at Helen's in Machias - 
can't miss that), FN 66 (Houlton), FN56 (Oakley), FN55 (just 
south of Patten), then overnight again in Bangor before we 
head back to MA. 
I will have 100 watts on 6 and 2 meters (SSB/CW) with my 
Kenwood TSB-2000/RC-2000 and loop antennas so we will 
operate while in motion with one of us driving and the other 
operating.  It's our first Rover attempt so I'm sure we'll learn a 
lot and eat some great lobster as well!
Dick, K1HC

See you on the air!

Video from 2012 NEWS BBQ

Last saturday I attended the Northeast Weak Signal Group annual BBQ and Microwave MDS test session. It's a great time, we almost always have great weather and the location is perfect. Lots of goodies for sale, I picked up a number of Items.

Here is a quick video I took of the microwave setups that people brought to test. I almost got irradiated by some 24GHz signals :)

Edit:  I also did a similar video back in 2007, that video is a bit longer and shows more of the setup and operation of the MDS testing. That video can be found here:

Sunday, July 15, 2012

2M Aurora to the Midwest

I worked a few stations on 2M CW via Aurora today. I heard many stations, but only ended up working three in grids EN60, EN70 and FN46. Here is a video of N9XG in EN60.

Friday, July 13, 2012

Upcoming VHF/UHF/Microwave Events

Upcoming VHF/UHF/Microwave events:

7/21-22/2012:  CQ WW VHF Contest - I'll be operating from the home QTH in FN42la

8/4-5/2013: ARRL UHF Contest - I'll be up at K1WHS in Maine

8/18-19/2012:  ARRL 10GHz cumulative contest - first weekend

9/8-9/2012:  ARRL September VHF QSO Party - I'll be up at K1WHS in Maine

9/15-16-2012: ARRL 10GHz cumulative contest - second weekend

Thursday, July 12, 2012

Being too reliant on technology...

The last few days I've been watching the APRS VHF Propagation map only to see the bands completely dead. Usually when I wake up in the morning the first thing I do is grab my iPad and look at propagation. This morning at 6am I did, saw the band dead, and decided not to get out of bed just yet. Just then, I heard a voice coming from my basement. I realized I never shut off my K3 the previous day, and when I went to investigate I found Joh, W1XX, calling a station down south, the band was open! I jumped on and made a few contacts with W4CLJ in FM18 and KD4AA in FM17. I then came to my senses and put the coffee on!
After the first cup I then ran with a number of stations. At one point, there were 4-5 frequencies in us, and it almost looked like 20m! The WA1ZMS beacon was pounding in at S8 and I was even hearing the W3CCX beacon, which is a first for this location.

The point is, I was relying on the APRS map to tell me if the band was open and I just assumed it was working! I should have been sitting in front of the radio, regardless of what the map was telling me.

I managed to get in contact with the fine gentleman who managed the map and he was able to get it fixed immediately.

I continued to work a number of other stations over the course of a few hours. This is the final log:

W4CLJ  FM18     394 miles
KD4AA  FM17    441 miles
KG4HOT FM07   522 miles
K1DQV  FM19    354 miles
K2DZM  FN20     228 miles
N4HB   FM17uu   400 miles
N3RG   FM29ki    282 miles
KO4YC  FM17fm  464 miles

Three new grids for me!

N3RG came on frequency and was very loud, here is a quick video of my QSO with him:

My only regret for today was that I'm still employed and my boss expects me to show up to work!

Saturday, July 7, 2012

Summer 2012 2M tropo continues

I arrived home Friday evening around 8:30 from my weeks long vacation to discover that 2M was open, and apparently, was open all day. I turned on the station and within a few minutes worked N3MK in FM27 and K3CNH in FM28. Both were loud, S7, and fairly consistent. The band was building as the evening went on, finally both N3MK and K3CNH were S9+10 by around 10:30pm. Here is a video of N3MK calling:

I had SpectraVue running with my SDR-IQ on the IF output of the K3. Here you can see how loud N3MK, K3CNH and the K4MHZ beacon were:

And finally, this is what the APRS map looked like.

My only regret was that there weren't more stations to work.

de N1JFU