Hf multi hop network for emergency communication
Download
1 / 13

HF Multi-hop Network for Emergency Communication - PowerPoint PPT Presentation


  • 130 Views
  • Uploaded on

HF Multi-hop Network for Emergency Communication. There are Maximum Useful Frequency (MUF) and lower Absorption Frequency (ALF) bounds for communication between tow terminals. HF communication is dependent on: 1- Frequency 2- Range or path length 3- Antenna elevation angle

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'HF Multi-hop Network for Emergency Communication' - nanda


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
Hf multi hop network for emergency communication
HF Multi-hop Network for Emergency Communication

There are Maximum Useful Frequency (MUF) and lower Absorption Frequency (ALF) bounds for communication between tow terminals.

HF communication is dependent on:

1- Frequency

2- Range or path length

3- Antenna elevation angle

4- Height of the ionosphere

5- density of ionization of the layer

skip zone:

Region between maximum ground-wave distance(30~50km) and closest point where HF are returned from the ionosphere.


Important frequency

f0

f

h

D

Important frequency

Critical frequency :

= the maximum electron density in a given ionized layer

Maximum Usable Frequency (MUF) :

D= the distance between the station h= height of the reflection point

Optimal work Frequency (OWF) :


E f1 at daytime
E & F1 at daytime

The Relationship between angle and frequency

F1 layer at 12:00

E layer at 12:00


E f1 at daytime1
E & F1 at daytime

The Relationship between frequency and distance

E layer at 12.00

F1 layer at 12.00


F at night
F at night

F at 22.00

Frequency and distance

Angle and frequency


Experiment

Using the antenna positioned in Honnjo campus

Receive the internationally broadcasted radio in HF band.

Experiment


Experiment equipments
Experiment Equipments

T2FD antenna

DSP Receiver NRD-545

(T2FD): Terminated Tilted Folded Dipole



Hf multi hop network
HF multi hop Network

  • Communication for long distance

      →HF wave

  • Communicate with neighbor station

      →Ground wave

  • Skip zone correspondence

      →multi hop

  • Merger between HF wave and ground wave

We analyze the model when data packet is transmitted using direct broadcasting.

The packet will be forwarded by HF multi hop in same frequency that have been received.

The purpose of our proposal system

To assure the data we transmitted can be received by all stations


Situation1 recover the connection

Situation1:Recover the connection

F

  • When the frequencies been changed, the distances will also been changed. Therefore the network can be newly construct.

E

A

B


Hf multi hop network for emergency communication

Situation2:skip zone access

F

E

A

D

B

Ground wave

C

In said A station skip zone

Stations in the skip zone can be reached by successfully usage of theGround wave and reflection on the ionosphere by HF band.


Experiment 1 2
Experiment (1.2)

HF coverage distance :

Experiment detail:

Stations: 1-fixed 2-moving (by car)

Elevation angle:height elevation angle

Frequency:low frequency

Expected result:

The distance of HFcoverage area and signal strength