Monthly Archives: October 2010

KA4UDX , Alan Spicer, Amateur Radio Contact – D44AC – 15 Meters (21Mhz) – 3577.5 miles

http://www.qrz.com/db/d44ac

QRZ Record 1145859
Lookups 93126 (100191)Mailing Label…
QRZ Admin D44AC
Last Update 2009-10-10 11:20:31
Latitude 16.884061 (16° 53′ 2” N)
Longitude -24.986343 (24° 59′ 10” W)
Grid Square HK76mv
Bearing 88.6° E (from KA4UDX)
Distance 3577.5 mi (5757.4 km)
Long Path 21279.4 mi (34245.8 km)
Web Page http://www.qsl.net/d44ac

D44AC-Google-Earth-Distance

D44AC-Google-Earth-Geography

—

73 de KA4UDX,

Alan Spicer

KA4UDX, Alan Spicer, Amateur Radio Contact – LU8SAN – 10 Meters (28.455 Mhz) – 4303.5 Miles

http://www.qrz.com/db/lu8san

QRZ Record 857405
Lookups 5204 (6461)Mailing Label…
QRZ Admin LU2SAB
Last Update 2002-06-24 20:15:41
Bearing 165.3° SSE (from KA4UDX)
Distance 4303.5 mi (6925.8 km)
Long Path 20553.3 mi (33077.4 km)

KA4UDX <-> LU8SAN – Google Earth Geographics and Distance

LU8SAN – Google Earth Geographic Location

* Note: There seems to be a discrepancy between my plotted (and distance ranged) location for LU8SAN, and he does not give Lat. and Lon. coordinates on his QRZ.COM web page. Email to his address on qrz.com also bounces. This is as close as I can get for now. Google Earth seems to have trouble finding many addresses in non-US countries by the street or postal address that non-US hams post on qrz.com. Unless they provide latitude and longitude information (many do) it is difficult to verify the location data. The QRZ.COM plotted location may be inaccurate, or my plot may be inaccurate, or both. Your Mileage May Vary.

—

73 de KA4UDX,

Alan Spicer

http://www.showmanagement.com/fort_lauderdale/event/

It’s Fort Lauderdale Boat Show time again here in Fort Lauderdale, Florida. I hope to get into the show at least one day of set of show days. See the above link for more information.

* This is ASMT – Alan Spicer Marine Telecom – Purveyors of fine marine Communications, Computer, and Marine Internet Products and Services including: Cellular, Satellite, WiFi, Onboard Networks, Navigation and other Computers and General Consulting and Support Agreement Services. +1 954-683-3426. * **Also ask about general marine electronics and electrical – in team with – IMEA / International Marine Electronics ** *

Fort Lauderdale, Florida, lives up to its nickname as “Yachting Capital of the World”, hosting the 51st Fort Lauderdale International Boat Show on October 28-November 1, 2010. With more than 3 million square feet of space over five locations, the show’s transportation network of bus shuttles, water taxis, and riverboats ensures attendees can easily navigate the boat show and its expansive waterways system.

Show exhibits range from yacht builders and designers to exotic cars and brokerage yachts. A wide variety of boats and sea vessels will be on display including runabouts, sportfishers, high performance boats, center consoles, cabin cruisers, flats boats, skiffs, express cruisers, sailing yachts, motor yachts, bowriders, catamarans, ski boats, jet boats, trawlers, inflatables, canoes, and extraordinary superyachts. Added attractions include The Blue Wild Dive Show, IGFA’s School of Sportfishing and Hook the Future’s Kids Fishing Clinics.

BOAT SHOW SCHEDULE
October 28-November 1, 2010

Prime Time Preview:
Thurs. Oct 28, 10am – 7pm

General Admission:
Fri. Oct 29, 10am – 7pm
Sat. Oct 30, 10am – 7pm
Sun. Oct 31, 10am – 7pm
Mon. Nov 1, 10am – 5pm

—

Alan Spicer Marine Telecom is based in Fort Lauderdale, Florida

Alan Spicer Marine Telecom and WiFiYacht.net

+1 954-683-3426

communications @ marinetelecom.net

* Life often immitates art, they say. And we came here in a time machine that you invented! And we have to get back to 1980… well 2000 something. It’s interesting that movies in the 1980′s portrayed big problems with computer security and here we are in 1985, no 2010, still trying to figure out that that’s a problem.

McKittrick: It might help to beef up security around the W.O.P.R. …

http://www.imdb.com/title/tt0086567/quotes

Movies in the 80′s portrayed large buildings being infiltrated by terrorists who came in the back door, as well as the front door that got left open: http://www.imdb.com/title/tt0095016/ but still terrorists flew in through the front door and destroyed large buildings after that.

http://www.pcworld.com/article/208581/google_to_tighten_privacy_policies_after_wifi_fiasco.html?tk=nl_bax_h_crawl

Now …

Google to Tighten Privacy Policies After Wi-Fi Fiasco

—

Alan Spicer Marine Telecom and WiFiYacht.net

communications @ marinetelecom.net

+1 954-683-3426

A computer doesn’t get happy … it doesn’t get sad. A program doesn’t think … it doesn’t know when it has been hacked. It just runs programs…  http://www.imdb.com/title/tt0091949/quotes

Newton Crosby: It’s a machine, Schroeder. It doesn’t get pissed off, it doesn’t get happy, it doesn’t get sad, it doesn’t laugh at your jokes…
Newton Crosby, Ben Jabituya: …IT JUST RUNS PROGRAMS!

A lot of things are computer programs these days. We all know that. A lot of things are digital as compared to things which don’t run through a computer, computer program, algorithm, etc. … but just purely put out a signal that is for the most part unencumbered and unprotected by any such digital systems.

There can be an algorithm (a method of doing something within a computer program) for a lot of things – including things recently discussed on here such as HDCP and CSS video content protection systems.

So what’s in an algorithm? a program?

A lot of programs nowadays are written in higher level languages such as “C” or “C++” (and many more). Most non-programmers (such as me for the most part) would be more familiar with the “Basic” programming system. All of these high level language (compilers or interpreters) are just another “program” or system of programs that runs on a “Computer System”. Computer systems can be all sized as you see with hand-phone portable computers these days, but also not to forget wireless routers and such which are also small computer systems. Even your DVD player and your television set have computer system components built-in to them. As you can tell by the discussions about content protection and scrambling systems. A lot of what can be done in hardware (such as DVD players and Television Screen Systems) can also be done in software on a modern computer system running a modern operating system – as is evident by DVD software players, MP3 and other music players, and general Movie Players in popular use.

At the core a digital system is just that digital. Digital meaning “binary” as in the binary numbering system is used to represent the actual “code” or “programs” and the information “data” that run on a digital system. Now that’s hard core! But that’s the core of how these things work. In fact memory used to be called “core”.

An algorithm, or program, or part of a program, is basically a method to accomplish something. A means to an end … to use a common phrase. An algorithm might be used to encrypt video data in a sub-part of a program (called a sub-routine), and another one might be used to do authentication and to exchange keys to allow decryption. Another part or algorithm (sub-routine) might be used to decryption once it has been authorized.

Things that they don’t want you to see, that they don’t want program crackers to see, might be obscured by an algorithm that encodes or otherwise protects a “private key” that they wouldn’t want generally or publicly known.

In a computer program, at the binary level, everything is written in “machine language”. That’s the only language that a computer system (a central processing unit, or CPU) understands. The codes used in machine language are called “Op Codes” or operation codes. Those codes are used to perform miniscule operations within the CPU. They might be manipulating bits, adding numbers, and storing small bits of information temporarily in little memory locations within the CPU called “registers” or back to the computer systems main memory – called “RAM”. Information is loaded (including program code) from RAM to the CPU, is manipulated, sometimes outputted to external devices (display devices, lights, modems, printers, and more) and results often stored back into RAM memory for further use.

Machine language – in the old days – could be entered in the front of a computer system at its main panel by flipping toggle switches to represent program instructions and data. But more often such machine language code is generated by a program called an “assembler”. So in order to create the program one would have to write the code in “assembly language” which is slightly above Machine Language but at the same core level. You would write OP CODES which are “Instructions” for the CPU from a specific CPU (or a CPU Family Group) “Instruction Set”. A help file or document on OP CODES from a particular CPU’s Instruction Set would give you the information to help you write “Assembly Language” programs for that particular CPU. Along with any hardware documentation for the larger computer system components that would be supporting that CPU.

So an algorithm would be doing very basic things in machine code (from assembly language code). A program would start at a particular address in memory. You could initialize certain temporary small pieces of data often known as “variables” because they could change over time during the execution of your program. You could have different sections in your program that could be considered “algorithms” within “sub-routines” that perform specific things. You can perform basic math and bit shifting on data in registers. You can jump between your sub-routines by testing for certain conditions by using CPU flags. For example to compare if a number I provide is equal to a known or stored value I could load something into the accumulator and compare it to another register. If it’s true that the values are the same – I could cause the CPU to jump within the program to another section of code, or not to jump if it is not true. For example in a small program that I have written (modified from someone elses program) for the Z80 CPU – I rotate back and forth LED lights like the Night Rider TV Show car named KITT. I decided to change the program to not only allow moving 1 LED light but to allow moving 1, 2, or 3 LED lights back and forth by changing front panel toggle switches (changing a certain condition reading an external input or influence and changing to a different sub-routing or algorithm based upon that change).

; 2-bit lights display toggle
LD      A, H
CP      3
JP      Z,LOOPB
CP      243
JP      Z,LOOPB
CP      115
JP      Z,LOOPB
CP      51
JP      Z,LOOPB
CP      19
JP      Z,LOOPB
; 3-bit lights display toggle
CP      7
JP      Z,LOOPC
CP      247
JP      Z,LOOPC
CP      119
JP      Z,LOOPC
CP      55
JP      Z,LOOPC
CP      23
JP      Z,LOOPC
; or fall back to LOOP “A”
JP     LOOPA

* Anyway that highlights how I can write a program section to jump or not jump – to change the behavior based on certain conditions … in this case the input of external hardware switches in an array that can be read as an 8-bit binary number (with a decimal number equivalent.) That’s all for now…

See also: http://developers.slashdot.org/story/10/09/29/0513225/HDCP-EncryptionDecryption-Code-Released

—

Alan Spicer Marine Telecom and WiFiYacht.net

http://www.marinetelecom.net and http://www.wifiyacht.net

communications @ marinetelecom.net

+1 954-683-3426

* Breaking News …

http://www.cable360.net/ct/news/ctreports/commentary/The-High-Def-Security-Crack_43683.html

High Definition, or High Bandwidth, Digital Content Protection has been cracked.

The master encryption key has been posted to the Internet. Normally  that key is not known. That key is used to generate other keys – those other keys which can be revoked if they are compromised. Now with the master key in the clear it will be easy to generate as many “other keys” as are needed. This is almost akin to how much more IPv6 address space there is in comparison to IPv4. There is now the capability of so many keys (some much Key Space) that it cannot be blocked.

I don’t know where this will go, but I’m sure the Linux crowd of programmers – wanting to keep adding video playing capabilities to Linux – that might be otherwise locked out by proprietary hardware and algorithm (security) blockages – could be very happy about this.

Fair Use – Being able to play content that you legally own any time, any place, on any device – is certainly desireable. But that for the most part is already happening. I think mostly the blockage by HDCP was to hardware DVD / Blue Ray Disc Players that could only play back High Definition Content to authorized devices. Meaning those that paid a fee. So companies with hardware devices pay some huge fee which is passed on to consumers in the price – all so that they can play discs which already belong to them or were rented. Devices or software players that didn’t pay that fee would not have the HDCP “software”. I guess then this can prevent you from playing your content into a monitor screen that wasn’t HDCP compliant. But what if neither the player or the screen was HDCP compliant? Is it still encrypted? I mean beyond what the other content scrambling system (CSS) [which already has had the same master key release crack in the open] does?

I strongly believe that everyone should properly purchase (license) their digital media such as video and high-def video on discs and other media holders. But being able to play that content anywhere … stream it throughout your house … or play it on your phone or portable player are Fair Use that should be allowed.

Anyway here is part of the article:

—> Alan Spicer

October 21, 2010
The High-Def Security Crack

HDCP, the security system for protecting high-definition video, has been compromised by the posting of the master encryption key to the Internet. This release has raised some fears that HD video will suffer the same fate as DVD after the encryption key was found in 1999. Intel, the inventor of HDCP, has reported that the key is legitimate. However, many believe that legal and technical barriers will keep HDCP relevant for the foreseeable future.

HDCP uses a public key cryptography mechanism, approved by the FCC in 2004, to protect the outputs of set-top boxes, Blu-Ray players and other entertainment devices. The system uses a sophisticated encryption key-management system to provide a chain of trust for protecting digital content. The master key, managed by Intel, is used to generate device-specific keys. Once content is encrypted by a studio, it only can be unlocked by device keys that have been generated by the master key.

A lock-out mechanism within HDCP allows Intel to revoke the credentials for compromised devices.  In order to lock a device out, content creators would have to include a list of revoked keys on any new Blu-Ray or broadcast HD content. But this mechanism will be ineffective in locking out newly generated keys because hackers could create a new key whenever an old one had been blocked.

(more at the cable360.net link above, as well as at the Wikipedia.org link above.)

HDCP uses three systems:

Authentication prevents non-licensed devices from receiving content.

Encryption of the data sent over DisplayPort, DVI, HDMI, GVIF, or UDI interfaces prevents eavesdropping of information and man-in-the-middle attacks.

Key revocation prevents devices that have been compromised and cloned from receiving data.

Each HDCP-capable device has a unique set of 40 56-bit keys. Failure to keep them secret violates the license agreement. For each set of values, a special public key called a KSV (Key Selection Vector) is created. Each KSV consists of 40 bits (one bit for each HDCP key), with 20 bits set to 0 and 20 bits set to 1.

During authentication, the parties exchange their KSVs under a procedure called Blom’s scheme. Each device adds (unsigned addition modulo 256) its own secret keys together according to a KSV received from another device. Depending on the order of the bits set to 1 in the KSV, a corresponding secret key is used or ignored in the addition. The generation of keys and KSVs gives both devices the same 56-bit number, which is later used to encrypt data.

Encryption is done by a stream cipher. Each decoded pixel is encrypted by applying an XOR operation with a 24-bit number produced by a generator. The HDCP specifications ensure constant updating of keys after each encoded frame.
If a particular set of keys is compromised, their corresponding KSV is added to a revocation list burned onto new discs in the DVD and Blu-ray formats. (The lists are signed with a DSA digital signature, which is meant to keep malicious users from revoking legitimate devices.) During authentication, the transmitting device looks for the receiver’s KSV on the list, and if it is there, will not send protected content to the revoked device.

HDCP devices are generally divided into three categories:

Source
The source sends the content to be displayed. Examples include set-top boxes, DVD, HD DVD and Blu-ray Disc players, and computer video cards. A source has only an HDCP/HDMI transmitter.[4]

Sink
The sink renders the content for display so it can be viewed. Examples include TVs and digital projectors. A sink has one or more HDCP/HDMI receivers.[4]

Repeater
A repeater accepts content, decrypts it, then re-encrypts and retransmits the data. It may perform some signal processing, such as upconverting video into a higher-resolution format, or splitting out the audio portion of the signal. Repeaters have HDMI inputs and outputs. Examples include home theater audio-visual receivers that separate and amplify the audio signal, while re-transmitting the video for display on a TV. A repeater could also simply send the input data stream to multiple outputs for simultaneous display on several screens.[4]

Each device may contain one or more HDCP transmitters and/or receivers. (A single transmitter or receiver chip may combine HDCP and HDMI functionality.)[4]

In the United States, the Federal Communications Commission (FCC) approved HDCP as a “Digital Output Protection Technology” on August 4, 2004.[13] The FCC’s Broadcast flag regulations, which were struck down by the United States Court of Appeals for the District of Columbia Circuit, would have required DRM technologies on all digital outputs from HDTV signal demodulators. Congress is still considering legislation that would implement something similar to the Broadcast Flag. The HDCP standard is more restrictive than the FCC’s Digital Output Protection Technology requirement. HDCP bans compliant products from converting HDCP-restricted content to full-resolution analog form, presumably in an attempt to reduce the size of the analog hole.

On January 19, 2005, the European Information, Communications, and Consumer Electronics Technology Industry Associations (EICTA) announced that HDCP is a required component of the European “HD ready” label.[14]
Microsoft Windows Vista uses HDCP in computer graphics cards and monitors.[15][16]

The A. Holes …

http://en.wikipedia.org/wiki/Analog_hole

The analog hole (also known as the analog loophole) is a fundamental and inevitable vulnerability in copy protection schemes for noninteractive works in digital formats which can be exploited to duplicate copy-protected works that are ultimately reproduced using analog means. Once digital information is converted to a human-perceptible (analog) form, it is a relatively simple matter to digitally recapture that analog reproduction in an unrestricted form, thereby fundamentally circumventing any and all restrictions placed on copyrighted digitally-distributed work. Media publishers who use digital rights management (DRM), to restrict how a work can be used, perceive the necessity to make it visible and/or audible as a “hole” in the control that DRM otherwise affords them.

The term “analog hole” was first popularized by the Motion Picture Association of America and some of its members during speeches and legislative advocacy in 2002; this term later fell into disrepute within the industry after it was abbreviated to “a. hole” (which was misconstrued as an allusion to the word asshole), thus being replaced by analog reconversion problem, analog reconversion issue and similar terms.[citation needed]

* Ummmm… uh oh, they called themselves a. holes?

See also: http://developers.slashdot.org/story/10/09/29/0513225/HDCP-EncryptionDecryption-Code-Released

—
Alan Spicer Marine Telecom and WiFiYacht.net

http://www.marinetelecom.net – and – http://www.wifiyacht.net

communications @ marinetelecom.net

+1 954-683-3426

KA4UDX Amateur Radio Contact: PJ7E St-Maarten 15M (21 Mhz)

PJ7E-QRZ.COM-St.Maarten

pj7e-Google-Earth



And the video of KA4UDX’s contact with PJ7E – Sint Maarten on 15 Meters Band

* A special note: Normally on SSB/HF radio we operate simplex – transmitting and receiving on the same exact frequency. In this case PJ7E was transmitting on one frequency and listening on another frequency slightly higher up the band. An operator that’s paying attention would hear that he was saying “350″ – pay close attention when you listen to the video and you will hear him saying that. So I used my dual A/B VFO capability and dialed in that frequency and went into “Split” mode to listen on his TX and transmit on his RX frequency. This is kind of like Half-Duplex. You can’t really listen while you are transmitting but you are in a duplex mode with split (2 independent) frequencies. You can do other things as well such as use independant RIT and XIT – Receiver Incremental Tuning and Transmitter Incremental Tuning to do similar things. U.S. Stations will often use XIT to go slightly “off frequency” to catch the attention of the DX station. You can also use a sort of “Social Engineering” by timing your transmit to “miss” the pack of all the other stations calling – or say something special that might be heard in his or her headphones to set you apart from the MANY other stations that are calling them.

It’s a game. It’s a sport. And you are there to win. Be polite but win. You want them to hear you … you want to get the contact in your log. (As a valid contact.)

—
73 de KA4UDX,
Alan Spicer

From http://www.qrz.com/db/pj7e (see my radio contact in my next post):

Joe, W8GEX and Craig, K9CT, are the co-leaders for the upcoming St. Maarten DXpedition. Joe and Craig are pleased to announce that they have been granted permission to use PJ7E for their 10 day operation scheduled to begin on October 10th. All indications are that St. Maarten will become a “New One.”

Check out our website at www.stmaarten2010.com

QSL to Sint Maarten 2010, Box 333, Bethleham, GA 30620-9989  with a SASE please.

Sorry, no EQSL’s

source

October 10, 2010 is a special day for Sint Maarten, as they gain their independence from Dutch rule.

To celebrate this historic event, a group of experienced DXers have teamed together to put this new country on the air.

* Alan’s Note: I think other islands in the Caribbean are also becoming DXCC entities for contesting / awards recognition for Amateur Radio Operators. I’m not sure what the politics is in all of this. But it’s great to get additional chances to contact these islands / island countries – via Amateur Radio!

* Additional Information:

12-October:  From the DailyDX:

The United States Department of State has added Curacao and Sint Maarten to the “Dependencies and Areas of Special Sovereignty” list.  This now clears the way for PJ2 and PJ7 to be added to the ARRL DXCC List.  Hopefully theARRL DXCC Desk will now have everything they need in order to make the official announcement as to the new DXCC Entities from the Caribbean.  Most likely it will be four new ones, as you editor has been predicting since this past summer.

http://www.state.gov/s/inr/rls/10543.htm#note11

—

73 de KA4UDX,

Alan Spicer

KA4UDX Amateur Radio Contact: KP2/N1WON – 15 Meters (21 Mhz) US Virgin Islands

* http://www.qrz.com/db/n1won

* http://dxing.at-communication.com/en/kp2-n1won_us-virgin-islands/

* KP2/N1WON US Virgin Islands:

N1WON will be active from US Virgin Islands 12-19 October 2010 as KP2/N1WON
He will be active on HF Bands
QSL via home call

US-Virgin-Islands_KP2-N1WON

US-Virgin-Islands_St-Croix_KP2-N1WON

KP2-N1WON-Google-Earth




And the video of KA4UDX’s contact with KP2/N1WON on 15M to St. Croix – U.S. V.I.

—
73 de KA4UDX,
Alan Spicer

You can make your Ham Radio go 4000 miles why not more miles on WiFi or Cellular?

* Well because those other things just don’t work that way.

Things that travel (communicate) by radio waves are on different frequencies – usually for a reason. The Amateur Radio Bands that I am using are for the most part of what is called “Shortwave”:

http://en.wikipedia.org/wiki/Short_wave

Shortwave radio refers to the HF (high frequency) portion of the radio spectrum, between 3,000–30,000 kHz.[1] Shortwave radio received its name because the wavelengths in this band are shorter than those used for medium and low frequency bands first used for radio communications.

Initially thought to be useless, shortwave radio now has many applications where the behavior of radio waves in the Earth’s atmosphere make long-range communication possible. Shortwave radio is used for broadcasting of voice and music, and long-distance communication to ships and aircraft, or to remote areas out of reach of wired communication or other radio services. Amateur radio on these frequencies can provide hobby, educational, and emergency communication.

* A radio waves “wavelength” can be expressed as: 300 / Frequency in Mhz = Wavelength in Meters.

* Or 984 / F Mhz and 468 / F Mhz for Wavelength in Feet (984 for full sized antenna, and 468 for a 1/2 wave sized antenna).

* You can use: http://www.onlineconversion.com/frequency_wavelength.htm this online site to calculate different Mhz and Ghz frequencies into Wavelengths and get an idea of the size of full and half size antennas (and such) at certain frequencies.

You will notice that the shortwave we are talking about isn’t really short by todays standards. A full wave WiFi antenna is just under 5 inches tall. A full wave antenna in the 10 meter Ham Band can be just under 35 feet tall. 417 inches.

* The lower frequencies used in Marine, Aircraft, Amateur Radio, and such bands for distance communications are bounced back by the ionosphere often at fairly great distances. In fact I have trouble talking on some of these HF bands to friends 60, 80, 100 miles away … when I can talk to someone 800 or 1000+ miles away just fine. That would the “Skip Zone” I guess.

http://www.comportco.com/~w5alt/antennas/notes/ant-notes.php?pg=2

Ionospheric Propagation. In this mode radio waves travel in a more or less straight line until they reach the ionosphere above the earth. Due to the ionization, the waves are refracted and when the ionization is sufficient, they will bounce back toward earth. When conditions are right, there can be multiple reflections with the signal bouncing between the ionosphere and the earth several times. That is how it’s possible to propagate signals over the entire world. This mode is mainly responsible for most DX contacts on the HF amateur bands.

As a result of the geometry, it is easy to see that to communicate at large distances, the radio wave needs to leave the antenna at a relatively low angle. That allows it to move the farthest distance before bouncing off the ionosphere. Obviously, if the signal goes straight up, then it will bounce straight down and not go anywhere. As a consequence, we generally want low angle radiation for DX, but somewhat higher angles for closer communications. This will be important when we evaluate antenna designs. Unfortunately it’s much easier to install an antenna that propagates straight up due to reflections from the earth.

* * * * Anyway most higher frequency radio transmissions – such as WiFi and Cellular only travel line-of-sight and due to lower power and dissipating signals (absorbtion by materials in the path) they don’t go very far. And that is for the most part by design. WiF wasn’t meant to go TOO far. Pushing it outdoors to a couple miles is stretching its range. But it can be done with the proper equipment. WiFi wasn’t meant to go TOO far because many people use it and they could interfere with each other if the signals went too far. Something called Frequency Re-use is done everday by people without really realizing it. They are shared WiFi Channels. Everyone has them.

The same thing happens with Cellular phones and Cellular Data / Internet Cards and devices. They weren’t intended to go 50 miles much less 4000. The cell towers are designed to cover a specific area. And the next area down the road could be re-using the very same channels. Antennas are down-tilted to keep the coverage within a certain range or area and to avoid interfering with other areas, and as before to allow re-use of those same channels or frequencies.

* * * * Satellite Communications – doesn’t use short range terrestrial like WiFi or Cellular or Skywave / Ionospheric propogation like SSB/Marine/Ham Radio … the antennas are specially designed (in higher Ghz frequencies) to cover from space (either low earth orbit or geosynchronous orbit) a certain “footprint” or area. There is no (intended) reflection or skipping of the satellite signals. But they are much weaker than WiFi, Cellular, and most other radio and television (terrestrial) signals that we would be familiar with. Because of this special low noise high-gain amplifiers and specially designed (often parabolic – dish) antennas are used to transmit and receive from satellites.

Radio Amateurs can also use Amateur-made (though quite professional) satellites – even at VHF and UHF frequencies. This can even be done by small Yagi (directional) beam antennas, some even hand holdable – such as the “Arrow Antenna”.

* * * * So there you have it. It is what it is. The services and what band they are on are what they are. And this was just a little attempt to explain the why of it all. If anything it might make you seek out more information than was presented here. And that’s a good thing.

—

73 de KA4UDX,

Alan Spicer

Alan Spicer Marine Telecom and WiFiYacht.net

communications @ marinetelecom.net

+1 954-683-3426