I’ve been playing with radio propagation the past few weeks. This is a propgation estimate for 2.4Ghz from the Cowee Tower site towards Sylva.
After a lot of research I finally have enough information to start some design and prototyping. If you missed the previous post, its located here. Here is a refresher of my design goals and info about how I plan to accomplish them. Continue reading “Underwater ROV (Part 2) – Beginning Design.”
At about the age of eight I remember waking up on Christmas morning and strolling into the living room to see a white Tandy box that would change my life forever. I remember it like it was yesterday. A while box was propped up in the living room along with a joystick, tape drive, and printer. I had wanted a microcomputer for over a year and now I finally had one. Over the next year I learned the basic language and got to experience my first twenty four hour or greater stints of uninterrupted programming. I remember days of digging through those Tandy catalogs and dreaming. An avid subscriber to Rainbow magazine, first BBS operator in my area, among other things.
I recently had to revive a ML850. Having lots invested in docking these I figured I might as well document what I had to do and take some pics to hopefully ease the pain of others. First to disassemble these you have to remove the bottom “pan” from the unit. The only two hidden screws are underneath the battery. You only need to take out the case screws and not the rubber cover screws. At the front of the pan there is a place to place a small flat head screwdriver to gently pry the pan off. The pan also has a wire that needs to be disconnected. Continue reading “Motorola ML850 Rugged Laptop Getac W130 Hard Drive Replacement”
Dark water diving initially to me was night diving. I have done a few dives in semi clear water with the worst being a few feet of visibility. Recently we did a training dive at Bear Lake and I got to experience what dark water diving was like. It was a sunny day, as we descended with our lights. At about 20′ it was almost pitch black and I needed a light to see anything. As we went further down on the anchor line visibility went to near 0. I could not see my hand or anything else for that matter. Even with my trusty dive light there Continue reading “Dark Water Diving – Scuba in the Dark”
I was recently reading the public safety diver magazine and noticed the small commercial ROV’s listed. Intrigued I went to each site took a look then noticed the pricing. They cost thousands if not tens of thousands to procure one. I thought to myself, what if I just want a simple one to for what I’ve see as a need? So I set out to do a quick feasibility study on build a small ROV for use with search and rescue and otherwise just something fun, useful, and inexpensive. Continue reading “Underwater ROV (Part 1) – Ideas and using off the shelf parts.”
I’ve been seeing various publications report that the iSlate is real and will be out on the market soon. The applications for a inexpensive tablet PC with a virtual keyboard is really appealing to a lot of applications I think about daily. For law enforcement it would be the perfect medium to complete paperwork, get signatures and be a general purpose device much more useful with a SSD than the current offerings of heavy rugged laptop currently used. The medical field tablets have been used for quite some time now. For technicians and tool makers this could be the perfect platform to provide a rich and powerful GUI to there wares via bluetooth or USB. Continue reading “Apple Tablet – AKA The iSlate”
Well if you have been following along you either have a M3ua link up and running or you really want one, peeking ahead to see what it’ll do. Well my first application was something very simple. I wanted to do my own CNAM lookups so I built a small TCAP query interface. It allowed me to pass a DN via IP and returned the Callers Name. Very useful when you have a VOIP switch and want to provide real cnam. Continue reading “SS7 – A-Link M3UA MTP2 . Now what?”
I won’t go into the basics of SS7 here but here is a quick tutorial to get you started if you need help.
At this point I assume you have a A Link or two of them, some hardware including some type of interface card like a Sangoma A101. If you have the gear, I prefer to use commercial gear to get m3ua rather than a link to the PC when possible.
I normally use the CentOS distro because its easy to get, has all the components and is very stable. Main things you’ll likely need in it are development tools and lksctp.
With the sangoma card you’ll want to download and install the mtp2 driver. There is sample code included and instruction on getting the MTP2 layer up and running. Continue reading “SS7 – A working A link. From MTP2 to M3UA.”
First my standard disclaimer. This blog is for information only. I don’t warranty any of the info and I’m rarely right so use common sense. With scuba gear always consult a professional.
About a year or so ago I picked up a used inexpensive Zeagle Ranger BC. I had used them at the squad and really liked it. On the first dive or two I noticed it was a bit different than the other Zeagle rangers folks had. The first thing was that it didn’t have a chest strap at all. My first thought was I was just going to purchase a upper section to gain the strap. After looking at other BC’s I realized that the buckle size was different as well. Thus I began my hunt on EBay for a used Ranger BC that had the chest strap. It took a few months but I did purchase one. After setting them side by side I could see many differences. Here is a short list: Continue reading “Zeagle Ranger BC – Some version history”
One of the biggest hurdle in working with SS7 is getting a link in a form to work with. Normally at most CLEC’s, it comes in on a 56k DDS line or if you are lucky its one of the channels (56k) on a DS1 line. Sangoma has the A101 card as well as MTP2 driver for linux that works great at getting the SS7 link into something you can use. If you have a DDS version of the link you’ll need a bit of Adtran or other gear to convert this to a DS1 and map it to a channel so the A101 can talk with it. Once you get the link to a PC thats where the magic happens. Continue reading “SS7 Getting started with a Link – The overview”
Many of you that know me are aware I’ve been pretty deep in the telephony world for quite some time. Everything from putting fiber into the ground to SS7 links. Over the years I’ve written a lot of code to do SS7 messaging and signaling either for gateway type applications or full blown ss7 data servers. Many have inquired about wanting SS7 but had no real understanding of what they wanted and certainly didn’t want to pay to figure it all out. I still think there is a void there between commercial full blown SS7 and the SS7 tinkerer. This article will an introduction be for the latter. Continue reading “SS7 for the common person…”
I recently had the opportunity to dive in one of our local rivers, the Tuckasegee. It was very close to dark by the time we arrived. There were three divers affording us a safety diver and several SRT (Swift-water Rescue Technicians) on the bank. Since at least two of us had never been diving in this kind of current much less in the dark it seemed we were well prepared.
It was a cold night in the 50’s and the water temp according to my Suunoto gage was 43 degrees. I had all of my 7mm gear on but could certainly feel the cold water. One difficulty I hadn’t thought about was getting myself in a 7mm suit with booties, no less, down to the dive site with my equipment. We had some dive handlers that helped but it was a careful stroll down the embankment thru heavy brush to get to the waters edge. Not something that was particularly fun in a wetsuit and booties.
After getting our gear on someone who knew how to do this gave us some quick advice and made it a point that it was just that, advice. He reiterated a few times that it was an acquired skill diving in current and navigating to the bottom. I of course had no real idea what he was talking about I just knew I was going to do my best to apply what he was saying once I got out there.
We had a target area about 25 feet out in the river we wanted to go over well. Initially I went up stream a bit then attempted to descend and begin the search. I quickly floated downstream past our target area and had to swim to the edge and walk back up. Not something with scuba gear on your back you would like to do many times in a row.
Second try, I went a bit further and tried to visualize my speed vs where I went at to determine if I was going to over shoot. First I dipped down into the water and completely emptied my BC, snagged an additional 8 lbs of weight as I walked by the bag, and found the secret. What is that you ask, well head down butt up is the best way I know to describe it. I forced my head down to the bottom. The current took care of getting the rest of me planted well enough with the pressure of the current pushing down on me to hold me in place. I could now crawl around and examine the bottom.
First small problem that arises. Am I even at the target site? I browsed around for a bit and realized if i didn’t keep my body laid out the way it was I would be whisked off downstream. Struggling around I finally noticed some light from the bank and used the lines of wash to establish I was near slightly upstream from the target area. The important point here is use the lines of the wash underwater to use a parallels along with light source on bank to tell where you are. I searched much of the target area and was able to hand around for about 10 minutes before making a mistake move that whisked me away quickly downstream.
Walking back up, I shared what I had learnt and headed back upstream. This time I perfectly “landed” the target area and reproduced it several times until I ran out of air and we packed up for the night. With each dive I got better and better at managing the current, my position, and my dive light. The only scary part of the night came while I was at about 15 feet searching. I was windshield wiper searching the bottom and suddenly a bright rainbow flash was suddenly right next to my head. It was a 12-16 inch rainbow trout swimming happily right next to my head. I almost spit the reg from my mouth. He just hovered around me like I was supposed to be in the water.
Getting into diving can be a very expensive proposition. I myself didn’t have a $5000 to throw around and figured that if I dug around on eBay long enough and did my research I could spot some solid equipment save some money. Well its turned out really well and figured I might as well share the experience.
First off BC’s are fairly easy to find. I’ve swapped out on eBay several times with just about every brand. The two I like the most are the Zeagle Rangers and the Mares Syncro (Rec) or Dragon. I really like these regs and they are sturdy BC”s that you can get a great deal buying used on eBay. I have purchased several and here is what I have learned.
Two big items to look for on the Zeagle ranger is does it have a chest strap and what size are the shoulder buckles. Older one don’t have the chest strap and have smaller buckles. It hard to swap shoulder sections with these. I would avoid them unless you just get a killer deal. I have one of these and it dives great but the chest strap is nice for an instructor wanting to pull you around where he needs you. Another thing is the Zeagles have a tendency for the glue holding the bladder to come undone. Get pictures of where the inflator hose connects to the BC and see if its come loose. Its fixable but I’d steer clear if you are a novice when it comes to glueing things.
The only real thing I’ve noticed that affects the Mares and Zeagle or any BC for that matter is look at the inflator. Get them to take it off and look for corrosion of the pull wire, valves, and hose connector. Plan when bidding to have to purchase a inflator hose and low pressure hose. As well as some cleaning.
Regulators are a piece of kit I was really scared to buy. I’ve learnt not to buy regs that are apart or not connected a first stage. Unless its new of course or getting sold separate. I’ve purchased many brands and the one that sticks out is Mares. In particular the proton series. I don’t know why but I’ve purchased several of these and they all work, all the time. Can’t say the same for any other brand. The last two sets I’ve purchased I got with everything including gages and computers. Absolutely no problems other than taking one of the octo’s for service for some minor free flow. It was a $15 repair and is as good as new.
Dive weights and belts. I don’t buy weight anymore. Its a pain and easier to just pick it up local. Belts can be had cheap. The only good deals I’ve got on weight was entire scuba lots.
Lights. I’ve picked up a number of really nice lights. The big thing to look for is assume you’ll need new bulbs. I’ve never purchased a poorly treated light but I have gotten a light with bad bulb. They don’t last forever. Also check the inside view of the light. I’ve never gotten a corroded light but I’m sure they are out there.
Wetsuits. I’ve never purchased a wetsuit or drysuit but booties, hoods, and gloves are plentiful and really easy to pick out using a pic or two.
Dive computer . There are two main types. Computers that have PSI and more of a dive watch that doesn’t have PSI. My favorites are the Suunoto Cobra and Vyper. The cobra has PSI and the Vyper does not. Both are similar in function. Be prepared to spend some money on an interface cable for a computer if you want to connect it to a PC. Most do not come with it. Also be mindful of what it takes to replace the battery. Some are a kit some you can just buy the battery.
After playing with diving in a pool for over a year I finally got to do my open water and high altitude certification.
Pool Skills – We all met up at the pool which had been ultra chlorinated. Many of us didn’t have all the gear we needed such as weights etc and had to beg borrow and steal. Everything went great until we got to the survival swim. MySelf and my brother had been going to the lake for years. Doing stunts and such from an inter-tube or wakeboard. We considered ourselves fish in water. At this moment however we were a few minutes into the swim and both on the verge of drowning. A simple skill neither of us really knew we didn’t know. After we both gave up, winded and beaten down, the instructor gets us back in the water demonstrates the proper technique and sudden we were masters at the survival swim. It was simple don’t exhale all the air which makes you float. The doggie paddle wasn’t needed.
Day 1 of Open Water Dives
Lake Jocassee in South Carolina was our dive spot. We went over all the gear and about signals etc. We were all taking in as much as possible as its a lot to remember. Not remembering could be a real problem when you are 40′ with no way to talk other than with your hands. I learned a lot in the first 20 minutes of diving. We had one that had trouble clearing at first. We did three dives this day all simple dives mixed with skills. Buoyancy seemed to be the big issue with everyone. Otherwise it was uneventful and a fun day of diving.
Day 2 of Open Water Dives
Lake Jocassee in South Carolina was our dive spot once again. The day started off with some humor and some engineering. Someone, I won’t say who, put there first stage on the tank and turned on the air. Unfortunately it was backwards and the air pressure was so great we couldn’t get the yoke to release. After some engineering, ribbing, and laughs it came off and was put back the right way. There were some equipment struggles at first at the surface so the instructor asked me to go own down with him for a bit. I was really surprised after getting to about 38′ when he signaled for my emergency ascent skill. I wasn’t ready for it but didn’t’ panic and completed the skill well. I think the only skill I haven’t mastered at this point is always remembering to blow bubbles when the reg wasn’t in my mouth. I forget to do this a lot so I’ve been spitting it out and bubbling to try and get it to become instinctive. Another person goes so I go down a few feet to watch. They did fine and the day was starting off really good. Then the same person that put there gear together backwards was up. He started his ascent on queue then after a few feet up panicked. Spit the reg out and did the quickest hand over hand up a rope I have ever seen. I’m just glad it wasn’t me. After the skills were complete we dove down to the “Junk” and actually for the first time just dove for the fun of it. Me and my dive buddy were open to dive around the junk and actually pay attention to what was around us rather than worry about skills. This is certainly what I signed up for and it was a great day of fun. Our instructor was great, he really knew what he was doing and really did a great job of showing us what do do and expect.