Cyberspectrum “#4”

*- Jesus Molina (@verifythentrust) will present on “Wardriving in the age of the Internet of Things with SDR”
*- Julian Arnold (@broadcrap) will talk in depth about “building a Doppler RADAR with cantennas and SDR”
*- Ief Kox (@iefkox) will talk from the other side of the world about “MultiPSK and use it to analyse all manner of interesting signals: ACARS (HFDL, VDL), STANAG 4285, ALE, AMTOR Navtex, Wefax, DGPS, SSTV” and more!

The Pirate Radio Survival Guide 1 & 2

Guide 1

by Nemesis of Radio Doomsday and Captain Eddy of The Radio Airplane Frequencies

The shortwave spectrum is a big place and each part of it has different characteristics. Knowing where you are and what to expect is a BIG part of successful broadcasting. The services and users on shortwave is staggering, but for all the activity there are selected parts of the spectrum where a Pirate and his Transmitter might find a listening audience!Groups of frequencies that support a particular service have traditionally been assigned a METER BAND designation that is the wavelength of those frequencies and can be used as a “generic” designation to refer to any or all frequencies of a particular band. I have researched pirate activity on the Shortwave bands and based on the usage patterns I am presenting, quite possibly for the first time, a complete list of “Pirate Bands” with unique and accurate Meter band designators. I hope that these are used and adopted by Broadcasters and Listeners.
Medium and Shortwave Pirate Bands
METER BAND FREQ. RANGE NOTES
185 Meters 1610-1640 kHz The expansion of the Broadcast Band to 1700 kHz
will see these traditional frequencies lost or
pirates may move to 1710 – 1750kHz.
90 Meters 3400-3500 kHz Some North American pirates have been testing
here recently, conditions on this band will be
best in the winter.
76 Meters 3900-4000 kHz Popular in Europe. NOT recommended for use in
North America!
74 Meters 4000-4100 kHz Not much activity in the Past.
51 Meters 5700-5900 kHz Used occasionally.
48 Meters 6200-6400 kHz Popular in Europe and used somewhat by North
American Pirates.
45 Meters 6400-6800 kHz see 48 Meters.
43 Meters 6800-7000 kHz Majority of North American activity is taking
place in the vicinity of 6955 kHz.
41 Meters 7300-7500 kHz 7415, 7445 and 7465 still see activity.
38 Meters 7500-8000 kHz Sporadic Activity Europe & North America.
32 Meters 9300-9500 kHz Europe & North America Active here.
30 Meters 9900-10000 kHz Europe & North America Active here.
26 Meters 11400-11500 kHz Europe & North America Active here.
22 Meters 13900-14000 kHz Europe & North America Active here.
20 Meters 15000-15100 kHz Europe & North America Active around 15050.
19 Meters 15500-15700 kHz
14 Meters 21450-21500 kHz Good place to experiment with new frequencies!
11 Meters 25900-27000 kHz It’s a jungle out there!

Guide 2

And there you have it! There are also a lot of isolated frequencies that see use like 12255 Khz. Radio Clandestine was the first and others have followed by operating inside the Shortwave Broadcast bands as well.
Survival Tip – Unless you are crazy, DO NOT operate your station in a Amateur Band! Not only will you be jammed but in all likelihood the FCC WILL BE notified within minutes! If you want to draw the WRONG kind of attention to yourself, this is the best way!
With all these frequency choices it looks like picking a spot to set up shop could be a daunting task. Not so, simply look and listen to where others are being heard and try these frequencies.
Success Tip – When choosing a frequency to use, monitor it for several days to determine who or what might be using it. A clear frequency is a good frequency!
For beginning pirates, I suggest that you attempt 41 Meters to start with. Don’t worry about the other bands yet. 41 is the easiest to start out with and has the least interference potential and biggest listening audience. You also will probably not have to modify your transmitter in any way to get going on 41 and if your just starting out, keeping things simple and easy as possible will help you greatly. It is difficult enough just getting on the air! With time and experience under your belt, you will develop the skills and confidence to tackle the other bands! For intermediate pirates, give 87, 74, 43, 22, or 14 Meters a try! Most of these bands can be hit without having to modify your amateur transmitter in any way.

Source: piratehamradio.blogspot.com

USB device cable shield connection – grounding it or not?

Colinb, an user from allaboutcircuits.com forum post this here:

I have been trying to understand how to ideally handle the cable shield
on a USB device. (Full Speed USB, in this particular instance.)

As seems to be the case with many signal integrity issues,
contradictory recommendations abound, each with its own unsupported
claims. Even authoritative-sounding sources such as Texas Instruments,
Intel, FTDI, and Cypress Semiconductor seem to disagree on the correct
way to handle the cable shield on USB devices.

Contrary to my initial supposition, the purpose of the USB cable shield
is not to protect the USB data lines from outside interference, but
rather to prevent the USB device from radiating EMI.

Here are some of the options that have been recommended.
Note that (2)—series capacitor to pass high frequencies only—seems to
directly contradict (3)—series ferrite bead to block high frequencies
only.

(1) Connect shield directly to signal ground.

– “Full speed devices use a shielded cable which requires that the
connector shell be tied to the ground plane.”
Intel. EMI Design Guidelines for USB Components. Sec 5.4 (p. 9).​

(2) Connect shield to signal ground through a capacitor.
(Possibly with high-value parallel resistor approximately 1 Mohm.)

– Connect shield to signal ground with 0.01 µF to 0.47 µF capacitor.
FTDI. Debugging FT232BM and FT245BM Designs. Section 3.2 (p. 11).​

 

– Cypress recommends a 1 Mohm resistor in parallel with a 4.7 nF capacitor.
Steve Kolokowsky & Trevor Davis (Cypress Semiconductor). Common USB Development Mistakes – You Don’t Have To Make Them All Yourself! Figure 7 (p. 7).​

 

– “Tying the shield directly to ground would create a direct path
from the ground plane to the shield, turning the USB cable into
an antenna. To limit the USB cable antenna effect, it is
recommended to connect the shield and ground through an RC
filter. Typically, R = 1MΩ and C = 4.7nF in Figure 3-5.”
Atmel AVR1017: XMEGA – USB Hardware Design Recommendations. Section 3.3.3 (p. 8).​

(3) Connect shield to signal ground through a ferrite bead.

– “Place a ferrite in series with the cable shield pins near the
USB connector socket to keep EMI from getting onto the cable
shield.”
Texas Instruments Application Report. USB 2.0 Board Design and Layout Guidelines. Sec 2.2.4 (p. 3). SPRAAR7 – December 2007.​

(4) Do not connect cable shield to ground on the device at all.

– As referenced in the AAC thread where to terminate usb cable shield?, Hardware Book says USB devices must
not connect the shield to their own ground.
Hardware Book. Universal Serial Bus: Shielding.

Whether or not the device has a metal chassis, and the handling
of chassis ground and signal grounds, (as well as how the USB cable
ground is connected to either one) is certainly important as well, but
this isn’t clearly discussed in most of the writings on USB cable shield
grounding.

The device I’m developing is a bus-powered device which will likely be
in an unshielded plastic enclosure.

Thanks in advance for any bits of wisdom on this topic full of
contradictory information. I recently posted this question on si-list,
and even there I got little in the way of answers.

Colin.

Source: http://forum.allaboutcircuits.com

//~~lo0king for the waves~~//