Antenna Handbook

How To Optical Fiber test Measurements Using OTDR ?

Optical fiber cables are tested for attenuation using the cut back method or back reflection method . The cutback method is mainly used in test at the manufacturing facility and the back reflection method is normally used in the field and in the manufacturing facility for some tests. An optical time domain reflectometer (OTDR) is the portable optical test set used in the field for pre- and post construction fiber measurements. The backscatter concept is illustrated in Figure 1

A lead-in or launch fiber is used to eliminate the effect of dead zone created from the OTDR fiber interface connector. A lead-in fiber is a fiber several hundred meters in length that connects the OTDR to the fiber being measured. It provides a useful fiber trace for the entire length of fiber under test. Since it provides backscatter power leading into and out of the initial fiber connection in the fiber undertest, a more accurate measurement of fiber length and total end-to-end loss can be made. The lead-in fiber is a commercially available OTDR accessory with a connector on one end to match the OTDR network interface and a connector on the other end to match the connector encountered on the fiber under test or in this case a bare fiber with a mechanical alignment fiber connector, such as an elastomeric lab splice. Lead-in fibers are useful to locate short distance faults and making loss/attenuation measurement in real time mode. This document explains howto use lead-in fibers.
One of the OTDR equipment come from Fluke Networks

Measurement Procedure.

Block Diagram

This is a schematic diagram of testing optical fibers using an OTDR with a lead-in or a launch fiber.

Procedure

Connecting Dummy Fibers / Pigtails to OTDR: Clean optical connector in end of lead-in fiber that will mate with the OTDR using isopropanol and lint free wipers. Connect it to the OTDR output so that a fiber trace can be observed. A square peak on the fiber trace (see Figure 3) will mark the start of the trace. Next to this peak OTDR traces should be a smooth with a continuous slope. Adjust the connector to obtain the OTDR trace as shown in Figure3.

reference : https://www.stl.tech/connectivity-solution/optical-fibre-cable/pdf/Measurements_in_New_Optical_Cables_(Pre_and_Post_Construction)-_New_-_Final.pdf

What is eero home wifi system ?

eero is smart wifi system that replace traditional wifi router, wifi extender and internet booster in One device eero system . eero works with eero TrueMesh Software App.

Unlimited Mesh

With TrueMesh, WiFi hops between eero devices to travel down hallways or go around walls. Most other WiFi systems only allow for one hop in any direction — so something as simple as a wall can mean that your devices can’t get the WiFi they need. eero allows for more hops with less speed degradation — so you can cover any home and navigate around any obstacle.

Solving Congestion

TrueMesh technology knows the signal strength between each eero in your home and calculates the best path from your device to the internet. If there’s a disruption on any part of your network — like if a pet knocks a Beacon out of the wall — TrueMesh dynamically reroutes traffic to keep it balanced. All this happens in the background so you don’t notice a thing.

Automatic Software updates

Normal routers require you to proactively install security patches — but let’s be honest, most of us never do that. eero automatically updates its encryption and security protocols to protect your network from the newest threats. You always have the latest features and security.

Control at Your Smartphone

With WiFi App by installing TrueMesh App,your network speed, which devices are connected and make sure each eero working properly. you can control all the eero function with your Smart Phone, works with Alexa, Amazon WiFi

Placing Additional eero

The eero app walks you through placing additional eero devices in your living room, bedrooms, kitchen, or hallways to bring WiFi to every inch of your home.

Optimize Your Home

From when your start activated eero, eero TrueMesh software begins learning from and optimizing for your space, devices, and network usage. So every device gets a reliable connection all the time, everywhere in your home.

eero come with 3 type :

eero is WiFi router and extender, and covers area up to 1,500 sq.ft

eero Pro

is tri band WiFi Router and Extender by cover area up to 1,750 sq.ft

eero Beacon

is WiFi Booster for expand your wireless coverage capability up to 1,500 sq.ft

With 3 pack eero as technical spec from eero, you can get covers area up to 5,000 sq.ft , this suitable for common house in America and Canada.

You can change the eero by mixed it as your coverage needs.

For example if you have house with 3000 sq.ft , you need 1 eero and 1 eero Beacon, or 1 eero Pro, and 1 eero Beacon.

DIY Six Stage Attenuator for High Frequency HF

If you have to deal with radio frequency more than very rarely, it is helpful if you can easily weaken the signals in discrete steps.

So you can e.g. Bring the output signal of an HF generator to a different level than would only be possible with the generator's adjuster.

There are many applications for a concealer when comparing or repairing receivers or with radio devices. Unfortunately, professional attenuator are quite expensive.

Doing it yourself is worthwhile here because expensive electronics are not required

The Circuit Diagram of Six Stage Attenuator from Elektor Elektronic July Edition 2017 in Germany language

Circuit Diagram

PCB Lay Out

Final Six Stage Attenuator Prototype with aluminum case

With Six Stage Switches for 0..31 dB in 1 dB Step

Prototype Final

Frequency Response 0....-31 dB

Radio Straight or Crystal Radio for Science Project or Hobbyist

OA70 / IN34 / IN60 is Germanium Radio, choose only one type.
Antenna high from Ground is high is possible, ground is a must to Steel Water pipe, or making one from a piece of copper approximately 1 meter down to the ground, so will be voltage between ground and radio wave pick up by antenna.

I have build this Radio and connected input speaker to line input notebook and running with Open Lab software and can pick up Radio Signal from about 6 km air distance.

====+ Parts List for +====

10 nF 1 Capacitor

VC 500 pF 1 Variable Capacitor

OA70/IN34/IN60 1

GND 1 GND
Termination Ground

108 Turns,12 Turns L Tap between 108 Turns and 12 Turns

8-2000 Ohm 1 SPKR or Earphone 8 - 2000 Ohm , you can get this in junk shop or at ebay.com

RF Connector Male and Female For Antenna Connection

50 Ohm Coaxial cable for Antenna

Electronic Project Box

Antenna for LW,MW,SW and AM

Sun Switch With Transistor 2N3055

2N3055 is Power Transistor and Amplifier Transistor for General Purpose and can act as Photo Transistor by cutting the "hat cover" of this transistor. This photo transistor function of 2N3055 can be taking the advantage as switching function with transistor. This circuit using 2 transistor which is 2N3055 and BD139. If there is no sun light or the light is not enough for Transistor 2N3005 to deliver, so R1 will give current to TR2 BD139 ,and this transistor will turn on Lamp on the Output of Circuit.

If The Sun Light which flows to "hat cover" of TR1 2N3055 enough, TR1 will deliver and will grounded Base of TR2 BD139 and will Turn Off The Lamp.R2 and P1 will improve switching system of the Transistors and The Light of Lamp Intensity could be regulated by P1.

At the below figure is Stripboard or Veroboard for the circuit. This Veroboard using DIY LC software.

Parts Lists of Components :
Transistor TR1 2N3055