Wireless Laser Control - improving reliabilty / safety

[loopee]

Paul

Unfortunately it’s just not that simple for several reasons (and the fact that you haven’t detailed what you’re connecting to or want you want to transmit, i.e connect to a QM2000.net box or transmit the analogue signals to the scan amps via wireless so I’ll assume networking to a laptop or QM2000.net)

To start with you can’t just simply swap out the chipset from a 2.4Ghz device and swap with some other frequency, it just doesn’t work that way. Changing to another frequency will require you to change the antenna to suit for one, and most chipset are not pin for pin compatible not to mention the additional/different components (crystals, capacitors, resistors, etc) required for the new chip. Then (for an Ethernet type device) you have the protocol stack and drivers you then need to modify

The other unfortunate thing about wireless is that for most countries around the world you can’t just pick a frequency, as most are reserved for licence spectrum holders, that is companies or organisation that spend a lot of money buying up radio spectrum to be used for transmitting public broadcasts or private links (TV, Mobile phone carriers, microwave links, and so on) and will spend a lot of money protecting their investment (or should I say a lot of your money) so we non-paying users of wireless are stuck with frequencies that are assigned to the ISM band (industrial, scientific and medical)
The ISM band is a set of frequencies initially reserved for use for research and such but was later opened up for public use and as such has no licensing and no regulation so anyone can use it, this is where the 2.4Ghz and 5Ghz bands fall that every man and his dog uses for everything from wireless baby monitors through to you wireless Ethernet connection on your laptop.
Check out Wikipedia for the frequencies - http://en.wikipedia.org/wiki/ISM_band

There are also other issues with changing the frequency, and typically it works in the manner of: the higher the frequency the higher the bandwidth and low signal distance (and won’t propagate through as much) or the lower the frequency the lower the bandwidth but will have a higher signal distance (and will be able to propagate through more), the other thing with the selection of 2.4Ghz and 5Ghz frequencies is that the signal coverage is limited and therefore minimises interference from a neighbouring access point.

The 2.4Ghz and 5Ghz bands also give a good ratio of bandwidth to coverage and is therefore used for wireless networking and depending on what part of the world you live in you will have access to multiple channels within the two frequencies to use (for example in Australia the 2.4Ghz band has eleven channels and the 5Ghz has eighteen channels in total)

So, from all this you’re best bet is to either be selective in picking a less congested 2.4Ghz channel when you set up in a location or start using the 5Ghz spectrum (that can still be susceptible to interference from other things like radar!)

Most laptops these days have a dual band card that will allow you to specify to only use the 5Ghz radio, the all you need is a dual band access point and then when you laptop connects it will only connect to the access point using the 5Ghz radio.

One other thing when buying an access point especially when you worried about reliability is to buy a decent brand as you will be able to configure things like Quality of Service, stronger security, channel selection and may provide you the ability to debug the airspace around itself when thing don’t want to play happily together.

There are other radio devices out there but these will also be based on the ISM spectrum bands as well and will be susceptible to the same issues and interference (although maybe not as much)

Troy

P.S. This maybe a stupid question but has anyone thought of using a laser based data link?
These are now capable of doing gigabit links so a 100Mb one should be cheaper, although still expensive in the scheme of things (but it does contain a laser!)

[andy_con]

how does the qm2000 wireless work???

[frank_1257]

Paul

Unfortunately it’s just not that simple for several reasons (and the fact that you haven’t detailed what you’re connecting to or want you want to transmit, i.e connect to a QM2000.net box or transmit the analogue signals to the scan amps via wireless so I’ll assume networking to a laptop or QM2000.net)

To start with you can’t just simply swap out the chipset from a 2.4Ghz device and swap with some other frequency, it just doesn’t work that way. Changing to another frequency will require you to change the antenna to suit for one, and most chipset are not pin for pin compatible not to mention the additional/different components (crystals, capacitors, resistors, etc) required for the new chip. Then (for an Ethernet type device) you have the protocol stack and drivers you then need to modify

The other unfortunate thing about wireless is that for most countries around the world you can’t just pick a frequency, as most are reserved for licence spectrum holders, that is companies or organisation that spend a lot of money buying up radio spectrum to be used for transmitting public broadcasts or private links (TV, Mobile phone carriers, microwave links, and so on) and will spend a lot of money protecting their investment (or should I say a lot of your money) so we non-paying users of wireless are stuck with frequencies that are assigned to the ISM band (industrial, scientific and medical)
The ISM band is a set of frequencies initially reserved for use for research and such but was later opened up for public use and as such has no licensing and no regulation so anyone can use it, this is where the 2.4Ghz and 5Ghz bands fall that every man and his dog uses for everything from wireless baby monitors through to you wireless Ethernet connection on your laptop.
Check out Wikipedia for the frequencies - http://en.wikipedia.org/wiki/ISM_band

There are also other issues with changing the frequency, and typically it works in the manner of: the higher the frequency the higher the bandwidth and low signal distance (and won’t propagate through as much) or the lower the frequency the lower the bandwidth but will have a higher signal distance (and will be able to propagate through more), the other thing with the selection of 2.4Ghz and 5Ghz frequencies is that the signal coverage is limited and therefore minimises interference from a neighbouring access point.

The 2.4Ghz and 5Ghz bands also give a good ratio of bandwidth to coverage and is therefore used for wireless networking and depending on what part of the world you live in you will have access to multiple channels within the two frequencies to use (for example in Australia the 2.4Ghz band has eleven channels and the 5Ghz has eighteen channels in total)

So, from all this you’re best bet is to either be selective in picking a less congested 2.4Ghz channel when you set up in a location or start using the 5Ghz spectrum (that can still be susceptible to interference from other things like radar!)

Most laptops these days have a dual band card that will allow you to specify to only use the 5Ghz radio, the all you need is a dual band access point and then when you laptop connects it will only connect to the access point using the 5Ghz radio.

One other thing when buying an access point especially when you worried about reliability is to buy a decent brand as you will be able to configure things like Quality of Service, stronger security, channel selection and may provide you the ability to debug the airspace around itself when thing don’t want to play happily together.

There are other radio devices out there but these will also be based on the ISM spectrum bands as well and will be susceptible to the same issues and interference (although maybe not as much)

Troy

P.S. This maybe a stupid question but has anyone thought of using a laser based data link?
These are now capable of doing gigabit links so a 100Mb one should be cheaper, although still expensive in the scheme of things (but it does contain a laser!)

Dear Loope, do you know if the gunplexxer microwave band used by radar and security alarm motion detectors using doppler is still open to experimenter usage. I remember years ago when you could buy horn kits for these and do amazing line of sight communications with these I had some project that I completed out of an old ARRL handbook years ago it was good for 20 miles if you had a vantage point to link from.

[mixedgas]

Dear Loope, do you know if the gunplexxer microwave band used by radar and security alarm motion detectors using doppler is still open to experimenter usage. I remember years ago when you could buy horn kits for these and do amazing line of sight communications with these I had some project that I completed out of an old ARRL handbook years ago it was good for 20 miles if you had a vantage point to link from.

10 ghz to 10.5 ghz is still ham, but 10.5 ghz ISM door openers are going away soon.
A gunnplexer drifts as much as 5 mhz a minute and I have the uWave counter to prove it, you want to use that for a laser control? 10 ghz is now gonna be crudded up with ultra wide band ultra short range one way links in the states, for things like mice . While we regularly get 30-50 miles on 10.368, it isnt easy and you need to phase lock the gunn diode to something, usualy a 106 mhz subharmonic. I do that too.

Steve

[loopee]

Dear Loope, do you know if the gunplexxer microwave band used by radar and security alarm motion detectors using doppler is still open to experimenter usage. I remember years ago when you could buy horn kits for these and do amazing line of sight communications with these I had some project that I completed out of an old ARRL handbook years ago it was good for 20 miles if you had a vantage point to link from.

Hi Frank_1257

To be honest I have no idea, I only play with wireless in the space of networking (and technologies based on it like location tracking)

I think Mixedgas has probably answered your question though.

[loopee]

how does the qm2000 wireless work???

I think you'll find the "qm2000 wireless" is a solution comprising of a QM2000 board, a QM2000.net adapter and a 802.11a/b/g/n wireless device (access point, workgroup bridge) connected to the ethernet port of the QM2000.net board

[andy_con]

so it uses normal wi-fi wireless then?

[frank_1257]

Dear mixedgas, thankyou for your reply In my day when i played with these we had a historically protected house here in Austin, Texas that was 3 stories very old and it was being used for satanic rituals by punk kids an old Jewish guy I knew who owned the house, paid me to hook up a set of these and a solar panel for an audio listen in alarm to notify him of vandals it took me a few months to get off ground but worked well. The gunnplexers were cheap, but the high gain horns were not. It just so happened the house was on a huge hill and the guys home was on another hill so it worked really well.

Do you know anything about usage of an old coherent rf modulator input interferiometer I picked up I tried some audio input for grins and aimed a hene laser though the stainless steel optical aperture I believe that it has some type of piezo in it. I did get demodulated audio from an audio listener magic ear with a miles military army war games target silicon photdiode connected. I know it was not designed for this a physics professor at ut austin told me that it was intended to be modulated at 10's of mhz he did not get into intended usage. last but not least does anyone out there know much about a spectra physics laser pumped head model number VSE 0135-3854 ?

Thanks in advance for any info it was produced last year.

Also does anyone know if laserscope gemini shutters are water cooled or not ?

[loopee]

so it uses normal wi-fi wireless then?

Yes. You supply and configure the wireles adapter and connect it to the ethernet port of the QM2000.net.

This then become the transparent link between the PC and the QM2000.

Pangolin's forums have details for doing this and I think it's also in a threat on this forum somewhere.

[andy_con]

so if the QM uses a wireless router why cantwe?