Packet Radio on 27Mhz (2011)(youtu.be) |
Packet Radio on 27Mhz (2011)(youtu.be) |
Packet radio, HAM, CB... it is all a mystery to me. Is there a beginner's guide somewhere on getting into this field for cheap?
When you're studying for your license, use my HAM Radio study guide for Android (https://market.android.com/details?id=com.tango11.hamstudy&#...). It's free and there are no ads; just something I did to give back to the community.
Something to consider, if that is accurate.
This is the spirit that made HAM Radio a success in the first place. I wish more of it would be still present.
Out of the same motivation, I have developed an open source APRS app for Android (http://aprsdroid.org/) written in Scala. It is available (for a fee) on the Market as well, but you can download the APK freely from the home page. :)
Of course, I'm not a huge fan of xastir. At this point, I want to build something new that's not GUI based and see if I can get something that's more useful outside of vnc.
See if a local library has a copy of the ARRL Handbook. There's also a ton of information available on internet. Many hams have blogs, projects, etc available to explore. Sometime back issues of Radio and ham magazines are freely available. http://www.ae5x.com/blog/tag/oldpubs/
There's a large number of kits and other projects that are simple and inexpensive to build. You can spend as much or as little as your budget allows and still have a blast. I've had a nice PSK31 chat with the US East coast from Texas with 3 watts and a simple wire antenna while car camping.
I'm hesitant in telling you to seek out a ham radio club. There's a bitterness among a small percentage of older hams that has discouraged a legion of folks from enjoying the spectrum. But with the internet, you can usually ignore these idiots and find some aspect of radio/electronics and communication with like folks.
http://www.arrl.org/new-to-ham-radio
They provide a wealth of resources. Keep in mind that most larger cities around the world also have ham clubs. Most have regular classes to help you get your license.
I didn't know it was written in scala, though. That adds extra awesome to it.
I'm really pretty interested in learning CW, but haven't been able to dedicate time to it yet. I'm not even quite certain how to pick any up. Most of the time I go looking, I don't hear anything (I've only got 2m/6m/70cm equipment, though).
Over the past few years I've done some reading/experimenting with meditation and I've found that high speed CW (morse) contesting puts me in a very relaxed state where I push out everything else from my consciousness. It's really quite awesome, and is lately one of the few things I can do that truly accomplishes this (the other is snowboarding down double black diamond powder).
The guy was eventually caught. His punishment was $20K and the loss of his license.
However, in all honesty, an encrypted communication can be claimed that you are working with digital modes with different compression schemes. The only real requirement here is to have a call sign in the clear in a common digital mode (CW preferred). Just dont be stupid and do a dump of a GPG encrypted block down the xmit.
For example, I regularly run channel 12 on my home wifi gear (european firmware). On my router, I have a sticker that states my callsign and EXPERIMENTAL. It's now allowed under part 97 tentatively. I also, out of respect, went to the 2 local HAM groups and stated what I was doing and where. If there's interference, I can change it.
Go look at the ACR specs for the chipset in your AP, and then realize that they're talking about the 'spacing'(for example) between ch 1 (centered at 2412MHz), 6 (2437MHz) & 11 (2462MHz) in the 2.4GHz band. Note that the center frequencies are 25MHz apart. In DSSS (1 or 2Mbps) or CCK (5.5 or 11Mbps) your radio has a signal bandwidth (or frequency occupation) of 22 MHz. Using OFDM modulation, the signal bandwidth is 20MHz.
Radios do not have an exact edge to their channel, and energy spreads beyond the edges of the channel boundaries. However, the overall energy level drops as the signal spreads farther from the center of the channel. The 802.11b standard defines the required limits for the energy outside the channel boundaries (+/- 11 MHz), also known as the spectral mask.
At 11 MHz from the center of the channel, the energy must be 30 dB lower than the maximum signal level, and at 22 MHz away, the energy must be 50 dB below the maximum level. As you move farther from the center of the channel, the energy continues to decrease but is still present, providing some interference on several more channels.
Ch12 is centered at 2467MHz. 11MHz up is 2478MHz. The US ISM band ends at 2485Mhz. In theory you don't need to be a HAM running under part 97 to transmit here, BUT remember that you're probably transmitting at 100mW (20dBm), so your radio's design is probably transmitting 50dBm into the edge of the band.
MOREOVER, the HAM band in-question is 2390-2450 MHz, so you're operating illegally when you're transmitting WiFi on ch12 (centered at 2467MHz!)
We've discussed what my proposal was with the 2 local ham groups. One person works for the FCC and finds non-compliant stations. From what he indicated, as long as I put "EXPERIMENTAL" on the device, and watch for interference (iow: be a good amateur operator), I can do this.
I've passed their kind requests, along with publishing what I am doing and with what wattage I am transmitting. I am also monitoring my emissions as I usually do when operating.
I'd also like to remind you that an evil device called a microwave oven transmits more as static on 2.4GHz broadband than my narrowband wifi.
A U.S. Federal Standard exists (and is used in most of the world), that limits the amount of microwaves that can leak from an oven throughout its lifetime to 5 milliwatts of microwave radiation per square centimeter at approximately 5 cm (2 in) from the surface of the oven after sale. (at manufacture, the limit is 1 mW/cm2 at 5 cm.)
US Dept. of HEW, FDA, Bureau of Radiological Health, “Regulations and Enforcement of Radiation Control for Health and Safety Act of 1968” paragraph 1030.10; Microwave Ovens pp 36-37 PHEW Publication No. (FDA) 75- 8003, July 1974
Now, what's the EIRP of your setup again? Assuming a 50mW (17dBm) radio and 2.2dBi 'short dipole' antennas, and maybe 1dBm of loss in the connectors/coax, you're at 18.2dBm EIRP at the surface of the antenna. Call it 65mW for grins.
At 2450MHz, you'll be down -14.2dB 5cm away. 18.2-14.2 = 4dBm, so 2.5dmW @ 5cm. You're lower than a worst-case microwave (but higher than anything that's allowed to be sold!), unless you fit high-gain antennas or high-power radios.
KD5FGA, btw. (also www.netgate.com)