Cathal

Site owner.

How to do speed cameras correctly.

We are often told that speed cameras are a tool to improve road safety. However, the method of implementation does not fit that requirement.

To do speed cameras correctly and use them as a tool to improve road safety, there are a few prerequisites.

  1. The locations that are high-risk need to be correctly identified, ideally to within a 50m stretch of road. This would allow camera monitoring to happen at very specific areas that are known to be accident blackspots. This does not refer to 20km lengths of road – as currently used for criteria of camera location selection.
  2. The locations of cameras must be publicly and freely available, and kept up to date. The location database must be unrestricted in use so that satnav companies can use that data in their products – allowing advance warning of known dangerous areas. Mobile camera locations must be advertised either in the database or on a specific website a number of days in advance. The camera locations must also have their local speed limit associated with the camera being visible in the database.
  3. Permanently installed cameras and mobile camera vehicles must be highly visible, with fluorescent and retroreflective paint, visible to drivers before entering the monitored area. Cameras must *not* be hidden or camouflaged, either deliberately or accidentally
  4. Camera locations must be clearly signposted at the roadside in advance of the installed location, and the area of camera visibility should be easily visible on the road.
  5. Camera location warning signs must have the local speed limit listed on the sign.

Following these would mean that the brief of improving road safety via speed-sensitive camera monitoring would be clearly met.

For example, let’s take a hypothetical place. Let’s say there’s a 1km straight road (100km/h limit) with a road junction in the middle (80km/h limit for the 50m either side of the junction), that has seen a number of fatal collisions over the previous decade. The correct way to put a camera on this is to put a signpost 300m either side of the camera location saying “warning Camera Ahead – 80 km/h limit. The camera should be a bright rescue orange colour with retroreflective strips on the camera housing.

This would ensure that the posted speed limit at the junction would be advertised and observed by drivers, and drivers that are over the posted limit would be caught.

There’s absolutely no value in stating that speed cameras are to protect, when they are used mostly with ambush tactics. The cameras currently in use do not look onto the areas with the accidents, they appear to concentrate on the areas that are actually accident-free. The zones used to determine the dangerous areas cover such a long distance that they are meaningless for specific area protection.

Let’s call the current situation in Ireland as it is. The current implementation of speed cameras, with the private operator using non-reflectively-marked vans, parking on the edges of straight stretches of safe roads, not advertising the locations – this can only be described as a money-making measure as it *cannot* fulfill the brief of improving road safety.

As an aside, it’s a great indication of the sneaky ethos behind the current operator’s operation of the cameras, where the vans have a hatched decal applied to the van surface. This decal, while appearing similar to the reflective hatching applied to truck trailers, is muted in colour and utterly non-reflective. It appears to provide only lip-service to safety, and acts to better camouflage the vans when parked up. This can only undermine any public confidence in this implementation of the system.

Daylight savings – some thoughts.

One of the definitions of timezone being correct for a location, is that the average Sun is due south at local noon on the clock. This means that there’s about the same length of time from sunrise to 12:00, as there is the length of time between 12:00 and sunset.

In historical times, the local church would ring the bells based on the local time, such that at 12:00 the Sun would due south. Of course, due to different places being at different longitudes, the Sun would be due south at different absolute times. There’s 4 minutes difference for each degree of longitude difference in the timing of the Sun being due south.

This caused some problems when the railways allowed relatively fast travel east and west as each location had been operating on its own time. There were some issues with timetabling and advertising the arrival and departure timings of trains as a result of those differences. It was then decided that the railways would operate on a time frame that was consistent for the train company such that when the train company clock said it was 9:00 in Paris, it was also 9am in Brest. Previously it would have been 8.32 in Brest as it’s 7 degrees further west than Paris. Each location with a railway station then started to use the railway clock as their local standard, and the countries started to operate on a consistent time zone.

The advent of telegraphy and radio was another pressure on places to have a consistent time that was the same set of numbers on the clocks in each location. It became easier to have time signals that would allow easier synchronisation of clocks.

Then, in the 20th century, it was agreed to standardise timezones across the world, with Greenwich in London to be the zero point. As Greenwich was defined to be the zero meridian of longitude, this meant that there were 24 time zones of an hour difference around the world, each separated from the next by 15 degrees of longitude. Once passing 7.5 degrees east or west from the center line of a timezone, it was at that point that the next timezone was due to start.

Of course there were some political and social considerations in play now, as it was not really useful to have a country split into multiple timezones. Portions of Ireland are far enough west that they should be in the GMT-1 zone, but it was decided to put all of Ireland into the GMT zone. France and Germany decided to work in the GMT+1 zone, even though Paris is close to the center of the GMT zone.

That’s a little bit on the history of timezones.

The current status quo is that Ireland is set in the GMT timezone, and we change to GMT+1 from approximately Spring equinox to the Autumn equinox. This means that in Dublin on July 1st, the sun is due south at 13:30. In Killarney on the same day the sun is due south at 13.43.

There’s a decision that has been made to stop the annual change of the clocks for DST, and that change is to be welcomed. The change has been seen to cause health issues due to the enforced body clock changes with changes in sleep patterns, and there’s also a well-proven uptick in accidents also mainly due to the sleep pattern changes forced onto people around the clock change.

One argument that continually gets put out there for DST is that it’s safer for the children at school, that they travel when it’s brighter or get more time in the light after school. It would be a much better change to change the start time of school to suit, instead of forcing a clock change on everyone.

I would suggest that Ireland go to GMT ans stay on GMT year-round Any businesses that operate with European groups can change their start and end times to suit the Eurpean office timings, e.g. starting at 7am and finishing at 4pm. It would be the same effect on our bodies as if we were GMT+1 and working between 8 and 5 in that timezone. The agricultural sector follows the solar day anyway, so the listed numbers on the clock are of no relevance to a cow’s desired milking time.

To recap: Ireland should go to GMT, and stay on GMT. Schools should be able to change their start times to suit the light conditions, if the lighting conditions are considered to be a timing requirement. Business should have the office openings as appropriate for their business. Doing all of this ensures that our clocks are correct as per the Sun.

Zurich is lovely.

I hear Zurich is lovely this time of the year..

Also it’s apparently a lovely drive from Ireland via ferry to Fishguard and using the Eurotunnel onwards to the continent. I also hear that parking is fun in that city..

More to follow depending on updates.

Boeing proxy fails the sniff test..

Read this link first – https://www.moonofalabama.org/2019/09/14000-words-of-blame-the-pilots-that-whitewash-boeing-of-737-max-failure.html

It’s a sane critique of a recent NY Times article that appears to be from Boeing PR by proxy: https://www.nytimes.com/2019/09/18/magazine/boeing-737-max-crashes.html . To be honest, I would have expected better from the likes of the New York Times.

And Boeing wonder why the European flight authorities will not be certifying the 737 MAX until the Europeans have tested and certified under European testing – any FAA certification understandably won’t be transferred given the debacle.

Flightradar rankings

A few weeks ago, I set up an ADS-B listener, started uploading to FlightRadar24 with the ID T-EINN18 , and I’ve watched my ranking go up and up..

As of this morning (August 20th I have the 43rd highest ranking of 130 in Ireland, 3rd highest Shannon uploader, and worldwide ranking of 6204 of 23,000, and going up by ~2000 positions a day at the moment.

I’m using a RaspberriPi 2b, an RTL-SDR dongle, and RTL-SDR 22dB LNA, and the antenna is a self-built colinear coaxial cable antenna with 8 116mm segments taped to the inside of an upstairs window. The software is dump1090 and the Flightradar24 uploader. I’m seeing ~850 aircraft a day, and an average daily max range of ~170 nautical miles (250km). Not bad for €50 or so of an outlay! I can see planes about 8000 feet above Dublin and 11,000 feet above Knock. The curvature of the earth combined with the lack of height of the antenna prevents me from seeing any lower.

The ADS-B signals are transmitted by every commercial aircraft and by most private aircraft, on a frequency of 1090 MHz. The information transmitted includes at least the ID of the plane and it’s current position and speed. When these signals are collected and processed, aggregator websites like Flightradar24 can show the current state of our aeronautical skies.

Improvements planned are the installation of an ADS-B specific filter/LNA from the RTL-SDR people that is en route. I did get one already but that failed within a few hours of installation so the warranty replacement was sought. That addition should mean that I have a bette chance of hearing planes through the house and increasing the range between my southeast and the west, as the window the antenna is in is facing to my northeast.

It is fairly interesting to see what is possible with some fairly basic items and a bit of DIY electronical knowledge!

KiwiSDR installed and running

So, I got myself a KiwiSDR. This is now connected to the random longwire I’ve strung across the rear lawn. It’s available on http://kiwisdr.swibble.com:8073

The KiwiSDR is a completely self-contained device, that consists of a Beaglebone Green micro computer, with an attached ‘cape’ that provides 30mhz of HF bandwidth to ~8 tuners. This means that (in one configuration) there are four tuners each with a waterfall available for use. Because the device is self-contained and accessible across networks without the use of a PC to host the tuning, there’s great flexibility in the device that can play and display the radio signals.

I’ve mine set in a configuration where there’s only two tuners with waterfalls, but there are another four allocatable tuners as a result. I’ve also got a number of those tuners operating as a reporter for WSPR signals on 60m, 40, and 20m.

Currently the antenna feeding this SDR is a ~20m random longwire strung across the rear lawn in a North/South direction, feeding 50m of coax cable and ending up at a Nooelec 9:1 unun. There’s a reasonably low noise level on this antenna for some reason, though the signal level is also a tad low. I have plans for either an Active Antenna amplified loop antenna, or something like a Wellbrook loop or a Bonito amplified dipole

My KiwiSDR is indexed on http://sdr.hu and available for public use.

Adventures in SDR in suburbia..


I’ve had a bit of time to try out a few different antenna ideas, and it’s been a very interesting learning curve so far.
Self-build antenna fun:
The first antenna attempt was a simple short randomwire of a few meters whiule sitting on the lawn with one of the laptops and the RTL-SDR dongle. I was able to get some SW stations from Saudi and Eastern Europe with that.
Second antenna build attempt was that I set up about 20m of insulated copper wire across the lawn, and fed a coax cable to the receivers directly from the centre point. This gave reasonable results, but definitely left a lot to be desired. I tried better grounding of the coax sheath, and then I realised that I should try a proper centre fed dipole with one side earthed instead of both sides going to the signal feed. This improved things a little bit, but was still a little underwhelming, most likely due to the horizontal orientation and the 2m of distance from the ground.
I rejigged the antenna in the third antenna attempt to become a proper ~20m long randomwire, end-fed to the signal feed in the coax, and earthing the coax cable at that point as well. This gave a good step up in sensitivity and signal strength. Then, after a long-awaited Ebay delivery of a 9:1 NooElec balun, things got quite interesting. I modified the balun to become a proper unun after breaking the centre tap to ground connection, and I installed the unun at the receiver. This is the current best state of the longwire, performance descriptions to follow.
I had ordered a 4:1 voltage balun as an experiment. With 10m of cable each side, I had tried to have a 20m dipole with a proper correctly matching balun in DX operation. However, the experiemnt was not a success as I found that there was no LW or MW, and the signal/noise levels as seen by the receivers was quite low – lower than the pre-balun randomwire. This antenna has since been disassembled, but I’ll hold on to that balun for a possible future transmission antenna.
After the purchase of ~200m of 0.5 square stranded cable, I decided to try a long loop around the perimeter of the property I’m currently living in. I ran ~80m of cable along the tops of the bushes and walls around the edge of the back lawn (maybe 2-3m average height), raising up to 6m height by using the soil pipe vent stack and a gutter downpipe as supports for the wire. I can’t yet put the wires muvh higher due to possible neighbour issues. Both ends of the wire loop were run into the radio room and attached to a 1:1 balun, and a length of coax then running to the receivers. The noise level is generally much higher than I had anticpated, and the signals are present at least. It’s a fairly good option at this stage if I had no other option. The balun in use has been shown to give some operation down to the LF area at least.
Miniwhips.
I started out with an AiExpress-sourced miniwhip, needing a 12v source, and 239 type connectors. I had a slew of 12v power supplies to hand, and found that the RFI generated by most of them was utterly abysmal and made attempting to use them for VLF through the lower end of SW almost impossible. . I did find the best of them, and it gave a clean enough power feed, and I did get to use that miniwhip to try to listen to things. Noise levels were still into the -60dBm with little in the way of useful SNR, and the signals were definitely not clear and listenable. I may yet disassemble this one and replace a few components to get a useful antenna.
Then, I ordered a Chirio miniwhip with options of either 9v PP3 power or 5v bias-t power. This was a thinner antenna, and had ~6m of coax already installed with an SMA connector on the end. This antenna gave much better signal levels and a lower noise floor than the Chinese miniwhip, but still had a lot of crackling. Adding a better earth connection to the SMA connector on the cheapy Chinese upconvertor dropped the noisefloor by some 10dBm or so. I’ve currently got the antenna powered from the USB socket on the Pi3 that is hosting the FC0012 dongle and the rtl_tcp server that is serving this across my network.
Antenna performances – as like-for-like as I can get them.
The miniwhip has a noise floor currently of some -103dBm. With the RTL-SDR at auto gain and using 2048kHz bandwidth, Shannon Volmet at 5505 has a signal level of -80dBm., giving an SNR of 23dBm. The sound of the signal is not great, but definitely understandable.
The horizontal loop with the 1:1 balun, with the Airspy, 2.5MHz bandwidth, linear gain at 15, zero visual gain, has the noise floor at -82dBm and the same Shannon Volmet signal at -71dBm, for an SNR of 11 dBm. The sound quality is poor, and not very understandable at all unfortunately.
The randomwire with the 9:1 unun, with the RSP1a using 2048kHz bandwidth, RF gain at 9, IF at auto, and visual at zero, has a noise floor at about -134dBm and a Shannon Volmet signal of -103dBm for an SNR of 31 dBm. This signal sound is definitely the best of the three antennas currently in use.
Receivers.
I have a handful of RTL2832U dongles that I used when I was getting started in the SDR world. I’ve some FC0013 tuners, as well as an E4000 tuner. I bought two RTL-SDR 820t2 dongles with the antenna kits, and those were an absolutely fantastic introduction into the SDR world. The direct sampling mode is reasonable, though the lack of gain control is a bit of a pain. I’ve got one of the dongles set up with an upconverter on the Chirio miniwhip, and serving to my network.
I later bought an SDRPlay RSP1a, and an Airspy/Spyverter combination. The RSP1a is pretty much the best bang for the buck SDR system that I’ve come across. VLF through 2Ghz without a break, no external upconversion required, usb-powered, and a lovely clean signal output. These are all very useful characteristics. The Airspy combo also has its place, it’s worth noting. Linux and RPi support is better, the hardware is physically smaller, and there are a few additional programs that are very useful such as the fast-sweep spectrum analyser and the ADSB client. Both of these receivers are currently plugged into the Dell Precision laptop, and being successfully served to my network via the SDR Console V3 server.
When I’m working locally on the Dell Core I5 laptop, I prefer to use the Airspy combo with the 10Mhz bandwidth. If I’m listening to one particular signal. I’ll pick it out with SDR# and using the decimation feature, to get the best possible SNR for that signal. The 10Mhz is very useful for the general browsing of signals and seeing which one I want to home in on.
Future plans:
I’ve spent some time looking at the KiwiSDR as a useful addition to my radio listening system. The 30Mhz bandwith visibility, the perfectly networked interface, and the extra plugins currently available, added to the four separate receiver channels possible, are all very enticing for my use case.
I also have my eyes on a better LW/MW antenna than I currentl have access to. I’m carefully eyeing up the likes of a Wellbrook ALA1530LN loop, or an Active-Antennas AAA-1 set as a quad loop, or even a Bonito Megadipole type of thing. I’m spending quite a bit of time looking round at the KiwiSDRs that are publicly available, to see how different setups can perform.

SDR fun

It’s been an interesting time recently, properly nerding out with the dabbling back into Software Defined Radio. Using a USB device, getting radio signals from around the world into the laptop, and doing interesting things from there. It’s pretty cool to be able, with the same device and hardware and antenna, to tune in the time signal on 60kHz, through getting shortwave radio stations from Botswana tuned in, to deciphering digital radio stations, to decoding the RTTY weather forecasts from the German weather service, to picking up faint FM radio stations from around the south of Ireland, to hearing Marine band transmissions, to seeing my car keyfob transmissions, to decoding and plotting airplane ADSB transmissions. All for under a hundred Euro for the hardware, and a few hours of learning.

It’s quite the rabbithole, is amateur radio stuff. Thinking about the HAM license and possible the VHF license as well, as those may come in useful for future outdoor adventures..

Scope problems..

My lovely new 20″ scope appears to need glasses. Seems as though Skywatcher didn’t make the mirror as well as they should have, and there is somewhere around one to two waves of spherical aberration present on the mirror. This is ruining the fine contrast on planets and making the scope a little frustrating to use. Currently working with the vendor to get a replacement mirror.

There is also another issue with the scope, where the primary mirror support structure has enough movement present under the change in altitude, to ensure that the scope cannot maintain collimation. My investigations so far suggest that the movement is present only in the interface between the glass and the central aluminium column that mounts the mirror to the rest of the telescope superstructure, so that’s another reason to require the replacement of the mirror as I cannot easily perform a repair on that interface, and given it’s under warranty I’m not going to touch that one.

The third problem I was having was with the quality of the GoTo computerised drive system. It turns out that one of the core components that supports the telescope “tube” had been bent out of place during a shipping accident, and was interfering with the correct operation of hte altitude portion of the drive. One removal and re-addition later, that component is now in the correct position and I’m now getting the desired target object somewhere in the eyepiece field of view after a slew.

My impressions of the scope are still good, though tempered by the (hopefully) temporary optical and mechanical issues present. There are some things I really like such as the ease of setup and takedown and the subsequent ease of storage that results from that. The drive accuracy once pointed on target means I can do lucky imaging of deepsky objects with some interesting results. The requirement for a small stepladder is not an issue for me on a lawn, but may be an issue on an apartment terrace. Now that I have the best of eyepieces and a Paracorr, I have some pretty low-power views when it is dark, but the high power views definitely have suffered with the aberrations present.

There does exists the capability for this scope to be a fantastic performer, just not yet.